All Savage 99's are marked with their Model, in the form of one or two letters, stamped into the front face of the action, on one or both sides (in the case of a two-lettered model like "EG") of the rotary magazine's axle bushing - viewable after first removing the wood forend.
If your friend's Model 99 turns out to be a 99F, and it's in as nice as condition as yours, but original/unmolested, it's value would be considerably more than yours - on the order of 50% more ($250), or 150% ($750).
If his is a .250 Savage ILO a .300, it's value would be 2x yours ($950-$1K, depending on condition).
The .300 Savage is (as posted above) basically a low-powered .308 Winchester, since the .308 was developed from the Savage cartridge.
No animal that I've ever shot with either has been able to tell the difference between the two , as far as I can tell - since they were all pretty much DRT.