With all other variables unchanged, the only difference is that the block reward is half as large as it is before the halving.
There are a lot of things to consider, though. Halving causes a sort of scarcity, which generally results in an increased value, so the market should compensate with a higher price per coin. Whether or not the halving gets negated by price changes remains to be seen, but it's possible the "reward" (in USD for instance) is similar, or the same, after the halving as it is now.
Regardless, your chance of finding a block is entirely based on your hash rate vs network hash rate and difficulty, which is not *directly* affected by the halving, so saying that your given effectiveness now (your two Apollos) will be half as effective after is not at all accurate.