At least in the 1990's Colt had some rubber Pachmayr type grips made for them by Vintage Industries.
These looked exactly like Pachmayr except they were made without the steel liner molded inside. These usually had a plastic liner.
As I recall, they made these Colt ordered replicas like the "D" frame Compac, the Gripper, and the Presentation types.
At least the latest version of the Compac has a banner with Colt in it on the bottom sides of the grip.
Genuine Pachmayr rubber grips are real rubber. Most other "rubber" grips are actually a polymer called Kraton. What the Vintage Industries grips were made of is uncertain, since it's impossible to tell the difference by looking.
As to whether these are "fakes", no one has ever made or is likely to make counterfeit rubber grips due to the extreme cost of the molds need to produce them.
So, these may not be Pachmayr, but they're almost certainly genuine Colt grips, unless someone went to the trouble of installing Colt medallions.