Not familiar with your aircraft, but V2(min) may be as low as 1.2 X Vs (or less), whereas Approach Climb Speed is 1.3 X Vs.
"Why is V2GA on the CRJ7 different to the V2 for climb? (on the CRJ2 they are the same)" - Perhaps because the Performance Engineering people for the CRJ2 opted for higher than V2 min (common practice to improve obstacle performance), whereas perhaps they opted for the lower speed option on the CRJ7 (common practice to improve Field performance).
Regards,
Old Smokey