Because paid maternity leave isn't a legislated provision, it is really up to the company to develop it's own policies around how they work paid leave. Often you are paid what you are working prior to leave although you may be entitled to what was in your original contract. You would need to check with your HR person to find out what the policy is around paid leave entitlements and also taking back to back maternity leave. You may find that you need to return to work for a certain period of time before you are eligible for a second lot of paid leave.