Don't create a new annotation table, just add a new group to the exist one

Scenario;

1. Open sequence, open the "PCR primer design..." tab.
2. Set "Melting point" minimum value to 54 and click "Start".
   Expected: the "PCR primer design for DNA assembly" annotation table has been created, there is one annotation group named "PCR primer design for DNA assembly".
3. Click "Start" again.
   Expected: there is one annotation table "PCR primer design for DNA assembly" and two annotation groups - "PCR primer design for DNA assembly" and "PCR primer design for DNA assembly 1".
   Current: there are two annotation tables and two annotation groups.