Content storage in SEP 12.1.6

I just accidently realized in my testing environment that content storage seems to slightly differ between SEP 12.1.5 and 12.1.6. While SEP 12.1.5 saves one full.zip file in the latest content folder and delta files in the older ones, SEP 12.1.6 saves full.zip files in the three latest content folders. That applies for all types of content.

Example: In <SEPM folder>:\Inetpub\content\{07B.....} (64 bit AV/AS stuff), the three youngest version folders are containing full.zip files, while the older ones only have delta files. In 12.1.5, only the youngest version folder contained a full.zip file.

I could not find anything about this change and would be curious why it happens.

OS: Win2008R2

SEP 12.1.6

Number of stored content revisions: 12