Acroonis True Image not splitting files

Recently I switched my backup drive from 160 gb to 500 gb. Now when Acronis (True Image 11.0) backs up my computers it splits the backup file into chunks about 4gb in size and names them by adding a digit to the name I give to the backup. For example if I name a file laptop8 it will store files named laptop81, laptop82 etc. Any ideas here why it would do this? I have done a restore to test that this is ok and it works fine. I told restore to use file laptop81 and it said restoring from file laptop8, so no problem.

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Jeff now retired