How do you take off bauer inline skates' wheels?

The skates have two screws on each side and I have matching Allen wrenches that fit but when I take one screw off, the other one just spins with the grooved rod through the wheel that holds the screws. I have tried turning the screws at the same time and I've tried holding one with a wrench and taking the other screw off like that and neither works. Any suggestions would be greatly appreciated! My skates are over 3 yrs old and desperately needs new wheels so any ideas that come to mind would be awesome!!!! Thank you!!!