Is this a new bug or a new type of unit

Two units received for processing, both showed as total time a data of 7hr 59':01"
All previous units, said 8hr 43' 33" (these used to take actual 8hr and 34' more or less)

However... now one of the units shows 6hrs 07'27" it was restarted at: Einstein@Home - 2005-01-31 08:50:26 - Restarting result H1_0083.4__0083.6_0.1_T23_Test02_3 using einstein version 4.72
But... time remaining to finish shows 12hr 08'50" ???????
So my question in the title comes again. Are we having a new bug or are these new type of units?