I never seen repros like these. If they are repros, they are very good quality.
As far as I understand they are made of Polyamid-6, a different material than bakelite. Here are few more informations:
http://pistole38.nl/p38-accessories/p38-grips
'' Polyamid-6 Grips
No company codes, trade names, serial numbers, or Waffenamts were found in the softer black grips that were seen predominantly on the late Mauser P.38s. These also were found to a much smaller degree on the late Walther P.38s. To date, it has not been proven that they have ever been found on Spreewerk P.38s. Typical characteristics of these slightly lighter weight and not-so-precisely-manufactured grips are their shiny, jet-black. Their external appearance is identical to the AEG grips. According to the grip’s internal configuration, two types (identified as I and II are known. On the lower inner surface of the left grip of both types, two empty circles are situated. The inner center of the right grip of the type I variety shows an inordinate warping, which corresponds to the feeding opening of the injection material. Other characteristics cannot be found on the type I right grip. On type II grips, the left and the right grip have matching markings (each marked with two circles in the inner lower half of the grip); less the inordinate amounts of warping found on the type I right grips.
It is not known to date where these grips were manufactured.''
I think they mention this variation on this page:
http://p38guns.com/Gripinfo.htm
'' The rest of Mauser production is the same as the Walther grips until Mauser switched to the soft, black plastic grips around the "v" block. These can be identified by two low circles on the left grip and mid grip sprue on the right grip as the most common. The inside of these grips will be a "dull" black, another variation is the right grip having the same two low circles as the left grip with a more glossy appearance on the inside of some sets.''
But I have never seen grips like mine.