Just a thought really, would having the 'doubled up' Lt slots be a new 'BOFF combo' they might start releasing in the future?
Basically it'd follow a pattern like this:
Cmdr and Lt. Cmdr slots are of the class of ship
Both Lt slots are of another area
The Ensign slot is the 'weak' spot as it were, of the third class.
The Steamrunner is the example I really use here:
Lt. cmdr tac
Lots of power, lots of hull tanking, very little science (bugged shield modifier or not). In turn, there could be the potential of other ships like this in the future, an example could be the Ambassador:
Lt cmdr eng
Just a totally made-up example, but something I wanted to mention.