Chronometer 

If both targets have the same name, you're pretty much out of luck. There's no way for an addon to reliably tell the difference between the two.

If the targets have different names, you should get timers for both of them.

The text option sets the text to be displayed on the bar. Use $s for spell name and $t for the target's name. By default it only displays the target's name ($t) and lets you figure out the spell by the icon. If you want both to be displayed, you could change it to something like "$t - $s" for "Target - Spell" or "$s: $t" for "Spell: Target".

All of the options should be documented in the readme.txt file in the Chronometer folder.

Also - a tip for a raiding warlock. In PvP or solo world stuff it can be nice to have the bars fade when dispelled (/chron fade) or when the enemy dies (/chron kill), but in a raid setting where you're killing lots of enemies with the same name and there are lots of other Warlocks' DoTs fading while yours are still ticking, you might want to turn those two options off.