we've had this problem before, you have to decide which of the two stems is the strongest then cut the other one off and very gently ease the one you've left on , straighten up & tie it to the cane, that's what we do anyway, hope this helps.
This happens to my plants occasionally too. Being greedy for crops I tend to keep both the shoots but tie them into the canes separately. I just make sure I give these an extra generous liquid feed when the tomatoes start appearing so that none of them go short.