Why is the data region shifted in multipanel in SciDraw? Is it a bug?

It may be hard to describe so here I provide a minimal example.

What I did here is to first create a density plot and then put a color bar aside(like what built-in PlotLegend does).

The list density plot is:

testdat = Table[x^2 + y^2, {x, 0, 1, 0.01}, {y, 0, 1, 0.01}];
testfig = 
 ArrayPlot[Reverse@testdat, DataRange -> {{0, 1}, {0, 1}}, 
  PlotRangePadding -> None, ColorFunction -> "TemperatureMap"]

The figure I got:

Then the colorbar:

testbar = 
 DensityPlot[y, {x, 0, 1}, {y, 0, 1}, AspectRatio -> 15, 
  ColorFunction -> "TemperatureMap", PlotRangePadding -> None]

Combine them using Multipanel:

Figure[Multipanel[{FigurePanel[{FigGraphics[testfig]}, {1, 1}, 
    XPlotRange -> {0, 1}, YPlotRange -> {0, 1}, 
    XFrameLabel -> Subscript[textit["[Alpha]"], 1], 
    XTicks -> LinTicks[0, 1, 0.5, 1], 
    YTicks -> LinTicks[0, 1, 0.5, 1], 
    YFrameLabel -> Subscript[textit["[Alpha]"], 2], FontSize -> 20], 
   FigurePanel[{FigGraphics[testbar]}, {1, 2}, XTicks -> None, 
    YTicks -> None, YPlotRange -> {0, 1}, YYTicks -> LinTicks[0, 1], 
    ShowTickLabels -> {{True, True}, {True, True}}, 
    XXFrameLabel -> textit["I"], 
    ShowFrameLabel -> {{True, True}, {True, True}}, FontSize -> 20]}, 
  Dimensions -> {1, 2}, XPanelSizes -> {1, 0.05}, 
  ShowTickLabels -> True, XPanelGaps -> 0.05, PanelLetter -> None], 
 CanvasSize -> {3.4, 3.4}]

The output is:

You see the data region is strangely shifted to the x=[-0.5,0.5], y=[0.5,1.5]. To be clear, if we make the PlotRange larger:

Figure[Multipanel[{FigurePanel[{FigGraphics[testfig]}, {1, 1}, 
    XPlotRange -> {-1, 1}, YPlotRange -> {0, 2}, 
    XFrameLabel -> Subscript[textit["[Alpha]"], 1], 
    XTicks -> LinTicks[-1, 1, 0.5, 1], 
    YTicks -> LinTicks[0, 2, 0.5, 1], 
    YFrameLabel -> Subscript[textit["[Alpha]"], 2], FontSize -> 20], 
   FigurePanel[{FigGraphics[testbar]}, {1, 2}, XTicks -> None, 
    YTicks -> None, YPlotRange -> {0, 1}, YYTicks -> LinTicks[0, 1], 
    ShowTickLabels -> {{True, True}, {True, True}}, 
    XXFrameLabel -> textit["I"], 
    ShowFrameLabel -> {{True, True}, {True, True}}, FontSize -> 20]}, 
  Dimensions -> {1, 2}, XPanelSizes -> {1, 0.05}, 
  ShowTickLabels -> True, XPanelGaps -> 0.05, PanelLetter -> None], 
 CanvasSize -> {3.4, 3.4}]

It is very obvious.

But if I only plot one panel, without the colorbar. Everything is normal again.

Figure[FigurePanel[{FigGraphics[testfig]}, XPlotRange -> {0, 1}, 
  YPlotRange -> {0, 1}, 
  XFrameLabel -> Subscript[textit["[Alpha]"], 1], 
  XTicks -> LinTicks[-1, 1, 0.5, 1], YTicks -> LinTicks[0, 2, 0.5, 1],
   YFrameLabel -> Subscript[textit["[Alpha]"], 2], FontSize -> 20], 
 CanvasSize -> {3.4, 3.4}]

So what happened when I use multipanel to combine a density plot and a bar legend? Why is the data region shifted? I am using SciDraw 0.07 and Mathematica 12.0. Thanks!