French word doubler comes from Latin pleo (To fill, to fulfill.)

Detailed word origin of doubler

Dictionary entry	Language	Definition
pleo	Latin (lat)	To fill, to fulfill.
duplus	Latin (lat)	Double (twice as much, or as big).
duplo	Latin (lat)	(Late Latin) I double.
dūplāre	Late Latin (LL)
dobler	Old French (fro)	(ambitransitive) to double. (by extension) to increase dramatically.
doubler	French (fra)	(Belgium) to repeat a school year. To double, duplicate. To double-cross. To dub. To overtake, pass.

Words with the same origin as doubler