とも～とも

AともBとも puts two possibilities side by side and says you can't settle on either. It most often ends in つかない, "you can't tell whether it is A or B": the thing sits somewhere between the two.

A and B are usually opposites or near neighbours, and they take the same form: two nouns, two adjectives, two verbs. The pattern is written and formal; in conversation you would say ほんき本気なのかじょうだん冗談なのか、よくわからない分からない.

とも～とも or か～か

きごう〜かか〜かわからない分からない just says you don't know which is true. AともBともつかない says the thing itself is in between, so neither label fits.

Usage notes

These go beyond つかない.

Didn't say which

With いわない言わない or いっていない言っていない, the person has not committed to either side.

Could be read either way

With とれる, a remark or an attitude can be taken as A or as B.