Every one has a dominant side and you will wear the spring on this side quicker thus making it feel softer
I normally suggest people swap the right and left spring every now and then
In my case it was normally 3 months or about 20 to 30 hrs
It does depend on how onesided a person is as some people never need to do the swap and others will need it regularly
Having said all of that how much time have you had on them as sometimes one spring will take longer to soften that another
I always put the stronger spring on my strongest foot
You can tell which is the stronger foot by which foot you use to run into a two foot jump the last one you puysh off on one foot will normally be the dominant one
Jason