When you paste special on the Mac version of PPT, what options are you given? I'm using PPT 15.31 and if I do Paste Special, it's as PDF so as to provide a vector image that can be re-sized and re-scaled as needed. I have not run into the skewing issue using this method either (direct copy -> paste special in PPT on Mac or using the Preview workflow I suggested in the previous post).
Attached is a screenshot of paste special on my version of PPT.
PPT-PasteSpecialOptions.png
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