– Idiom / Proverb / Idiomatic
This expression means you have two alternatives that are equivalent or indifferent; or, it doesn’t matter which one your choose because they are really the same.
The expression comes from the fact that half a dozen is an expression that means six. Supposedly, the earliest known use of the expression occurred in a journal kept by a British naval officer, Ralph Clark, in 1790.
In this case, what happens if you keep talking about two alternatives in a different ways, you might end up with more alternatives, or maybe something else perhaps?