in:

"one is/are two"

and in:

"two is/are one"

Are they the same? It is a stupid question I know but I have it stuck in my head. It came up in two semi-famous quotes ("two caesars is/are one too many" and "if one is/are two then I am the pope".) that I mostly remembered but in my then state couldn't recall exactly. Another question: the first quote is translated of course. If latin uses "is" and english calls for "are" (or the reverse) is it good style to translate exactly or change?

thanks,
bill