yes there is a side-by-side ~14400 parellel pack item that was used for photo applications, it is the first place that i snagged a AA sized li-ion, before they even made AA li-ion sizes available.
BUT
you want them the Long ways, so there are bunches of tricks you can do.
A) use one li-ion 14500 , and one conductor that fits the hole, a spacer AA. 1/2 the capacity all the volts.
B&C require flashlight rewiring, or packmaking, and an astute observation of its electrical connections, and attention on safety
b) put 2 14500 batteries nose to nose, and rewire. (ok rewire first) like:
{=====][=====}
|+3.7. . |-........|+
[=====}{=====]
|-. . .. . |+3.7.....|-
looks dangerous and stupid right? but it is actually how you would parellel them with wire, it is just a matter of rewiring , and insuring that any Ground are respected. like if the CASE is ground, then you would want to use method 1 there. you still have to grab the power off the center.
c) stack them normal, but insulate them from eachother proper, and run a sliver of a wire past them, a Wire that will maintain insulation on impact. basically parelleling them in the SHAPE of a series stack. at the bottom or the top you fully insulate , and present the light with your new conductor that connects both properly.
probably with method B or C a person might be wise to make a "stick" with both batteries inside effective insulation, so they can remove it as one piece. any assembly using B&C would want to survive impact , or it would be unsafe.
being parellel the 2 batteries could be charged as one item. as the pack aged, a person would want to check to make sure it was holding voltage and charging, any one cell item failing would be the pack failing.
