What is this: a dual CAP?
It's a 10V 100uF 3-leaded tantalum capacitor from Kemet (T396 series -- see Kemet's website and TTI). The "K" with the bars above and below is a trademark of Kemet. The yellow encapsulation and the stencil font of the numbering are consistent with Kemet capacitors as well, but I can't say for sure whether other companies have copied them.

Their circuit diagram shows two ground leads, presumably to reduce ESR and inductance (although it seems like if you really want to reduce ESR and inductance you should use a surface mount capacitor)

Aha, this is what they say about the three-lead design:


  The three-leaded design (the anode is in the center) enables operators to insert the capacitors into printed circuit boards correctly without having to visually determine polarity. This timesaving device also eliminates board damage that may result from incorrect insertion.