Two words
It is very likely a compound number duo + decem
decem NUM 2 0 X X X CARD
decem, decimus -a -um, deni -ae -a, decie (n)s NUM [XXXBO]
10 - (CARD answers 'how many');
du.o NUM 1 2 NOM P M CARD
du.o NUM 1 2 NOM P N CARD
du.o NUM 1 2 VOC P M CARD
du.o NUM 1 2 VOC P N CARD
du.o NUM 1 2 ACC P M CARD Early
du.o NUM 1 2 ACC P N CARD
duo -ae o, secundus -a -um, bini -ae -a, bis NUM [XXXAX]
2 - (CARD answers 'how many');
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Credits:
This, our local install of the popular standby Whitaker's Words, is possible thanks to the resurrection of the venerable project at William Whitaker's Words, where you will also find extensive documentation. The corresponding GitHub repository is where you can submit issues about missing forms and analyses.
This web interface by Walter M. Shandruk.