some slightly inaccurate advice above…
RH shifter – any MTB shifter is fine (of the right speed of course…)
LH shifter – the SL-R440 shifter is the one if you want it spot on.
An MTB shifter pulls more cable – you can get it to work on a double though, as cynic-al points out, but you’ll need to adjust the limit screw on the mech to stop the overshift onto the small ring.
Levers – any cantilever or flatbar levers. V levers will not be a good idea with DPs due to having too much cable pull. You’ll have a hard lever and sod all power. Even the Avid SD levers on their ‘softest’ setting (smallest pivot length) are still fairly hard and weak.
Look out for some Dia Compe SS5 or SS7 – lovely levers.