Hey Saleda,
A picture would really be nice, with info about the condensing pressure, load, cooling water outlet temp, and how the vacuum system is set up. It sounds like you have two driers sharing the same condenser.
To really assess your existing existing condenser performance you need to check the cooling water outlet temperature- if this is high the condenser is working but maybe just overloaded. If the cooling water outlet temperature is low then maybe there is a heat transfer problem.
It is hard to answer without knowing the system and what is limiting the condenser. Splitting and trying to balance the vapor flow via some weird unbalanced piping can be a challenge. If pressure drop across the condensers is not critical, then putting the additional area in series but with its own supply of cooling water is going to be a good option: this is series on the process side, parallel on the cooling water side.
The amount of acetone to be condensed seems fixed, but if you have air or N2 leaks into the system it will make the vapors hard to condense and lead to acetone losses.
best wishes,
sshep