It should. You don't have to carry UM on multiple cars because the coverage will apply to you no matter what car you're in. But if you do carry it on multiple cars, the coverage can stack. If you have 25/50 UM on 2 cars in your house, you can receive (as an individual) up to 50k in UM benefits (25+25). It is typically just cheaper to have 50/100 on one policy though.
Thats pretty much what we did. I was paying for lower amount per vehicle on 4 vehicles. Dropped all but one and jacked up the coverage and saved some money