Not sure if you mean two policies from two of the main insurers or one from the likes of hospital Saturday fund and another from a say laya.
We have 3 policies. One main with Laya, one with HSF and a work related one. The latter pays out on both day to day expenses and hospital bills while the HSF mainly pays out on things like GP fees , dental etc. but do pay towards nightly cost of bed in hospital. the only rule is that you must submit ORIGINAL receipts when claiming from all three but the bottom line is that you are entitled to claim from all three. I don't see why it should be otherwise given that we pay yearly to all three.