Which ever cyl has the least resistance will move first.
One cyl might be leaking.
You can do a cyl load test by disconnecting the hoses from one cyl if you have two, and cap or plug the hoses.
Then remove the hose from the base end of the test cyl and then try and retract more.
You are checking to see if fluid comes out of the base end port.
If it does, that cyl is bypassing and you need new seals.
Then check the other cyl.