
Are |

I wasn't aware that there had been errata, but yes, it does seem like it has been overlooked. That said, considering turning themselves into others is really all the doppelganger has going for it, it might be that they decided that it should still have the additional bonus.. If so, it should be specified as an additional racial bonus, of course.

jimibones83 |

If I remember right, polymorph use to grant a +20 to disguise, which makes sense with the dopplegangers +20. If you look it up in the CRB now though it states that it only grants you a +10. Apparently there was an errata at some point, I just heard about it today.
That's exactly what I was thinking though, if it was suppose to be there it would be specified.

Are |

One possible reason for the discrepancy is if the CRB errata in question was fairly recent, and if it was after the last Bestiary errata. In which case, it won't be updated for the doppelganger (and presumably other creatures with change shape) until the next Bestiary errata (which will come when the current printing is close to sold out).

jimibones83 |

Alter self use to be a +20. I just found a convo on the boards before posting this about the errata changing it to a +10. If yur certain you have a first print though, it wouldn't hurt to check it for a +20, thank you.
In case yur wondering my specific personal reason for pursuing this, There was a half doppelganger race in 3.5 that I converted over to PF using the rules in the ARG. I'd also like the +20 if there's a way to get it. If there's not then something needs fixed to justify the doppelgangers +20.
I know the first response is probably that since mines only half doppelganger then he only gets half the bonus, but that's not the right way to do things. If its the same ability it should he the same bonus. If the doppelganger has a different reason for his to be higher then that's fine with me, but it needs to be defined.
I kinda think that it is indeed an oversight that didn't get changed when alter self got changed, but that the +20 should stay by giving it some sort of enhanced shape change that functions as alter self but with a +20.