Thanks Scook - can you elaborate on what the first and second instances are/mean and if there are more than two? Many thanks

Insert TTS-1 into a project. It is the first instance of TTS-1 in the project.
Insert another copy of TTS-1 into the same project. This results in a second instance of TTS-1 in the project.
 
Each time a synth plug-in is inserted into a project a number is appended to the name so that each copy (or instance) of the same synth plug-in can be uniquely identified.