I bought a pair of new shock absorbers for my car today. When i went to the workshop and open up i did a compression on the pistons. i found that one of the shock piston return faster than the other. Both are of the same brand and specs. What could be the cause of it?
It would be helpful to know what car these are for and what location they are fitted in.
Remember that on most applications, the return of the suspension to it's "normal" position is done by the spring, not the damper. All that the dampers are there for is to absorb the compression from bumps.
What you'd be better doing is looking at how they respond to compression as this is where they're doing their "work".
Return rate on new shocks out of the box is irrelevant. It's how they perform once installed that matters. Two shocks can have two different rates right out of the box and work perfectly fine in the vehicle. It all depends on how they were stored.