If the servos are a good match this scenario is actually quite common. It often is the result of linkage setup and it goes much deeper than just "Linkages seem Free" :

Are both aileron horns positioned so the hole that used by the pushrod lined up even with the hinge line on both sides?

Are the control horns in the proper and exact same place on each side"

Are the pushrods on the aileron horns the exact same distance from the hingeline on both sides?

Are the aileron pushrods the exact same distance from the servo output bushing on both sides?

Are all pushrods completely free of all flexing, be honest and test by pushing the control aginst the servo??

Good mechanical setup and geometry is vitally important and often overlooked in the ARF age also when folks start modifying things.


John