Dictionaries built with DebianPts:dictfmt / DebianPts:dictzip (often called .dict.dz) contain timestamps:

This file was converted from the original database on: 
  $DATE
dictzip gzip-compresses the dictionary and includes a timestamp in the header.

= Solution =
   
Call dictfmt with --without-time to prevent the timestamp in the dictionary.
See Bug:776430.

In the case of dictzip a patch is needed, maybe the flag --no-name (-n).