Hints to distinguish between V1 and V2 sim cards:

SIM cards issued before JUNE 2002 most likely are COMP128v1 SIM cards

Phone book capacity more than 250 entries most likely are COMP128v2 SIM cards

The assumptions made above based on my testing results with SIM cards available in Hong Kong, it might not applicable on all SIM cards in different countries

When two or more SIM cards with same number (original and cloned) are in used:
Both phones can dial out but NOT in the same time

Only the latest dialed out or powered on phone can receives calls, the other
phone will not ring

If one phone is officially turned off (e.g. by switch off the power button), the
other phone can't receives calls even though it's still power on, the other phone
must make a call in order to make it can receives calls again.

quted from