This may have already been mentioned earlier in the thread, but do they both have the same part number ?
If not then there has to be a difference.
It's an assembly the compensator with N/S & O/S cables fitted
Looking at spec (on ebay listings ) the cable appears to be the same length BOTH sides 1550mm 1550mm
the 15MM difference on my BRAND NEW cable may be a manufacturing defect
It's a QH aftermarket cable ,15mm over 1550mm is 1%
that said , maybe the OP has a similar manufacturing defect
or the cable HAS stretched one side
or it's NOT fitted or adjusted correctly
$19.50 EBAY £32.30 ebay clicky sorry to mislead , but the cable I have spare
IS 15mm difference
(I laid it flat ,tight on the floor ,see saw level )