Are Oct4 and Oct3 the same protein?

The best review I can find is the one by Wang and Dai 2010, conveniently titled starting with "Concise review".

From the beginning of the abstract:

The human OCT4 gene can generate at least three transcripts (OCT4A, OCT4B, and OCT4B1) and four protein isoforms (OCT4A, OCT4B‐190, OCT4B‐265, and OCT4B‐164) by alternative splicing and alternative translation initiation

and from later on, in the introduction:

It is well established that OCT4 gene (official symbol POU5F1, also known as OCT3, OCT3/4, OTF3, and OTF4) functions as a master regulator in maintaining the properties of pluripotency and self‐renewal of ES cells

I take from this review that OCT4, OCT3, OCT3/4, whatever you want to call it, all refer to the same gene. However, this gene does have splice and translation variants. It seems that when talking about these variants, you will see them differentiated using A/B/B1. An older paper and some that cite it, Takeda et al, 1992, refers to the splice variants as OCT-3A and OCT-3B. If not noted, you can expect that the paper is considering them all together regardless of whether they call it OCT3 or OCT4.

I did find one thesis that treats Oct3 and Oct4 as separate proteins, renaming them from the A/B terminology, but they cite only the Takeda paper for this, which does not do the same. It seems more likely to me to be a mistake.

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Takeda, J., Seino, S., & Bell, G. I. (1992). Human Oct3 gene family: cDNA sequences, alternative splicing, gene organization, chromosomal location, and expression at low levels in adult tissues. Nucleic acids research, 20(17), 4613-4620.

Wang, X., & Dai, J. (2010). Concise review: isoforms of OCT4 contribute to the confusing diversity in stem cell biology. Stem cells, 28(5), 885-893.