The obverse looks like it might be, but the reverse doesn't look the same - e.g. the curvature on Providentia's body.
It SHOULD be a reverse die match also, because this obverse die was used only with one reverse die to strike this type... Ro, you have some incredible Pertinax Sestertii there!!! I am envious :-D The style and toning of the first piece is totally adorable while your second specimen features the rare reverse variant with both hands reaching for the star!!! I am working on a big writeup on the Sestertii of Pertinax which I will publish here once my coin actually gets here. May I try a die analysis for your coins too while I am at it?
Mine is a bit worn, but would be interested in the comparison: RI Pertinax 193 BC AE Sestertius rome mint LAETITIA RIC 17 C 21
I think it is a double die match. Here's an overlay animation of the reverses. In the last frame I erased bits of the OP coin's reverse so you could better see how it matches up with the archive coin. The minor differences can be attributed to differing angles of photography, wear, slight size mismatch when editing for this gif, etc.
OMG I seriously wish I had your skills, TIF The other coin (Paris, Cabinet des Medailles) is Woodward´s plate coin for his obverse die Nr.11 and reverse die I D for the type in his study "The Coinage of Pertinax" (Num. Chron. 1957), so you saved my day!!!! Thank you thank you thank you thank you!!!
Today I found six more Pertinax Sestertii (all sold in auctions during 2009-2017) that also look like double die matches to mine: Is that just an unusually high "survival rate" or need I worry?
In my opinion the fact that there are a few coins struck from the very same die as yours is no reason for concern. After all, yours look legit, and so do the others you have shown. Actually, when you think about, sestertii of Pertinax are actually not that rare. I counted 25-30 examples of the PROVIDENTIAE type alone in acsearch. One can therefore assume that there are 2-3 times that number out there in collections? That would not be unreasonable. So to have 10-20 or so from the same die is not out of the ordinary, in my opinion. On a general note concerning fakes of Pertinax: asse and dupondii of Pertinax are much scarcer than his sestertii and denarii, but the larger coin gets all the attention (and the prices reflect it). The coin doctors and counterfeiters also seem to have focused primarily on the larger bronzes, as well as the denarii, and have not bothered with the asse and dupondii. Therefore, I am quite happy with the As I have in my collection. No worries about it being legit.