WowAce

Abilities that strike with both weapons, such as Mutilate, Obliterate, and Stormstrike, produce data for each weapon, as in "Stormstrike" and "Stormstrike Off-Hand".  An option to combine them into one ability would better reflect actual play and would be a very welcome addition.  The only downside that comes to mind is that the abilities can crit separately, and displaying those details while also combining the damage might be difficult, but if I had an option to combine the bars and forego those details entirely, I'd gladly take that option.

I haven't checked Recount, but Details! doesn't seem to do this.  Warcraftlogs.com does this and displays a Stormstrike with averaged numbers, as well as nested Stormstrike and Stormstrike Off-Hand with their specifics.