It definitely looks like a 'bug', but I suspect a work-around is to just enter it as two separate 1095-As (January through August for one, and September through December for the other.
You might need to add an "a" and "b" to the end of the policy number so TurboTax doesn't give another error (don't worry, that policy number does not show up on the tax return and is not actually transmitted with the e-file).
