Biblatex: Two bibliographies with different styles and sortings II Part 3

You may want to try the following solution. It requires severe rewriting of internal commands, but the style you want is quite different from what numeric-comp normally does.

documentclass{article}
usepackage[utf8]{inputenc}
usepackage[T1]{fontenc}

usepackage[backend=biber,
  style=numeric-comp,
  labelalpha, defernumbers,
  locallabelwidth]{biblatex}

usepackage[colorlinks=true,citecolor=blue,urlcolor=red]{hyperref}

%Append keywords to identify different bibliography entries.
DeclareSourcemap{
  maps[datatype=bibtex, overwrite]{
    map{
      perdatasource{biblatextest1.bib}
      step[fieldset=KEYWORDS, fieldvalue=primary]
    }
    map{
      perdatasource{biblatextest2.bib}
      step[fieldset=KEYWORDS, fieldvalue=secondary]
    }
  }
}

renewcommand*{multicitedelim}{addsemicolonspace}

letbibmacro{cite:num:comp}{cite:comp}

newbibmacro{cite:alpha}{%
  printtext[bibhyperref]{%
    printfield{labelprefix}%
    printfield{labelalpha}%
    printfield{extraalpha}%
    ifbool{bbx:subentry}
      {printfield{entrysetcount}}
      {}}}

renewbibmacro*{cite:comp}{%
  ifkeyword{primary}
    {usebibmacro{cite:dump}%
     ifnumgreater{value{cbx@tempcntb}}{-1}
       {multicitedelim}
       {iffirstcitekey
          {}
          {multicitedelim}}%
     usebibmacro{cite:alpha}%
     iflastcitekeylocal
       {}
       {multicitedelim}%
     setcounter{cbx@tempcnta}{0}%
     setcounter{cbx@tempcntb}{-2}}
    {usebibmacro{cite:num:comp}}}

makeatletter
newcommand*iflastcitekeylocal{%
  ifnumequalc@citecountc@citetotal}

renewbibmacro*{cite:init}{%
  globalboolfalse{cbx:parens}%
  globalundefcbx@lasthash
  globalundefcbx@lastnumber
  globalundefcbx@lastprefix
  globalundefcbx@secondtolastprefix
  setcounter{cbx@tempcnta}{0}%
  setcounter{cbx@tempcntb}{-2}}

newcommand*{ifsamelabelprefix}{%
  iffieldundef{labelprefix}
    {ifundefcbx@lastprefix}
    {iffieldequals{labelprefix}{cbx@lastprefix}}}

renewbibmacro*{cite:comp:comp}{%
  renewcommand*{multicitedelim}{addcommaspace}%
  ifsamelabelprefix
    {ifnumequal{thefield{labelnumber}}{value{cbx@tempcntb}}
       {savefield{entrykey}{cbx@lastkey}%
        savefield{labelnumber}{cbx@lastnumber}%
        addtocounter{cbx@tempcnta}{1}}
       {ifnumequal{thefield{labelnumber}}{value{cbx@tempcntb}-1}
          {}
          {usebibmacro{cite:dump}%
           ifnumgreater{value{cbx@tempcntb}}{-1}
             {multicitedelim}
             {}%
           printtext[bibhyperref]{%
             iffieldequals{labelprefix}{cbx@lastprefix}
               {}
               {printfield{labelprefix}}%
             printfield{labelnumber}}}}}
    {usebibmacro{cite:comp:end}}%
  setcounter{cbx@tempcntb}{thefield{labelnumber}}%
  globalletcbx@secondtolastprefixcbx@lastprefix
  savefield{labelprefix}{cbx@lastprefix}}

renewbibmacro*{cite:dump}{%
  ifnumgreater{value{cbx@tempcnta}}{0}
    {ifnumgreater{value{cbx@tempcnta}}{1}
       {bibrangedash}
       {multicitedelim}%
     bibhyperref[cbx@lastkey]{%
       ifdefcbx@lastprefix
         {ifdefequalcbx@lastprefixcbx@secondtolastprefix
            {}
            {printtext[labelprefix]{cbx@lastprefix}}}
         {}%
       printtext[labelnumber]{cbx@lastnumber}}}
    {}%
  setcounter{cbx@tempcnta}{0}}
makeatother

DeclareFieldFormat{labelalphawidth}{mkbibbrackets{#1}}

defbibenvironment{bibliographyALPHA}
  {list
    {printtext[labelalphawidth]{%
       printfield{labelprefix}%
       printfield{labelalpha}%
       printfield{extraalpha}}}
   {setlength{labelwidth}{labelalphawidth}%
    setlength{leftmargin}{labelwidth}%
    setlength{labelsep}{biblabelsep}%
    addtolength{leftmargin}{labelsep}%
    setlength{itemsep}{bibitemsep}%
    setlength{parsep}{bibparsep}}%
    renewcommand*{makelabel}[1]{##1hss}}
  {endlist}
  {item}

begin{filecontents}{biblatextest1.bib}
@BOOK{BookA03,
  author    = {Author Ät{"a}},
  title     = {Some Title},
  publisher = {Some Publisher},
  year      = 2003,
}
@BOOK{BookB02,
  author    = {Author Bb"{a}},
  title     = {Some Title},
  publisher = {Some Publisher},
  year      = 2002,
}
@BOOK{BookB09,
  author    = {Author Jjj},
  title     = {Some Title},
  publisher = {Some Publisher},
  year      = 2002,
}
@BOOK{BookB10,
  author    = {Author Kkk},
  title     = {Some Title},
  publisher = {Some Publisher},
  year      = 2002,
}
@BOOK{BookB11,
  author    = {Author Lll},
  title     = {Some Title},
  publisher = {Some Publisher},
  year      = 2002,
}
end{filecontents}
begin{filecontents}{biblatextest2.bib}
@MISC{LinkC01,
  author  = {Author Ccc},
  title   = {Some Title},
  year    = 2004,
  url     = {www.test1.com/bild.jpg},
}
@MISC{LinkD04,
  author  = {Author Ddd},
  title   = {Some Title},
  year    = 2001,
  url     = {www.test2.com/bild.jpg},
}
@MISC{LinkD05,
  author  = {Author Eee},
  title   = {Some Title},
  year    = 2004,
  url     = {www.test3.com/bild.jpg},
}
@MISC{LinkD06,
  author  = {Author Fff},
  title   = {Some Title},
  year    = 2001,
  url     = {www.test4.com/bild.jpg},
}
@MISC{LinkD07,
  author  = {Author Ggg},
  title   = {Some Title},
  year    = 2004,
  url     = {www.test5.com/bild.jpg},
}
@MISC{LinkD08,
  author  = {Author Hhh},
  title   = {Some Title},
  year    = 2001,
  url     = {www.test6.com/bild.jpg},
}
@MISC{LinkD09,
  author  = {Author Iii},
  title   = {Some Title},
  year    = 2001,
  url     = {www.test6.com/bild.jpg},
}
end{filecontents}
addbibresource{biblatextest1.bib}
addbibresource{biblatextest2.bib}


begin{document}
The first two citations autocite{LinkD07,LinkC01}
and autocite{BookB10,BookB11,BookB09}.

Mixing both primary and secondary autocite{LinkD08,LinkD04,LinkD05,BookB10,BookB11,BookB09}.

The others are autocite{LinkC01,LinkD08,LinkD05,LinkD06,LinkD07}
as well as autocite{LinkC01,LinkD04,LinkD05,LinkD07,LinkD08, LinkD09}
and autocite{BookA03}.

printbibliography[env=bibliographyALPHA, title=Bibliography, keyword=primary]

newrefcontext[labelprefix=techstringadddotspace]
printbibliography[title=References, keyword=secondary, resetnumbers]
end{document}