Thread:Yatalu/@comment-30384903-20150904193659/@comment-4142476-20150904215919

Well additionally (not that this is why I use a template but) templating interlanguage links also allows for a quicker overview of all pages that have interlanguage links using Special:WhatLinksHere.

But if you want a very specific answer to that question: no, you can't. Technically even with de: and de2: you're no longer making interlanguage links of the same language. You're adding an extra (nonexisting) language called "de2" that just also happens to be German.