New to apple trees---question

I planted my first two apple trees---honeycrisp and yellow delicious both about 5ft tall from the nursery.

The honeycrisp had flowers on it, received a really bad frost after planting and even with it covered the flowers all died

Now the honeycrisp about three weeks later has new buds with one opening to a flower today--why is it blooming again?

Hi Andrew,
Welcome to Permies.
I can only assume that the new flowers were ones that were not quite ready to open previously and were then delayed by the frost.  In the first few years of planting you should not let the trees ripen very many fruit anyway, so you haven't lost too much this year.  Concentrate on developing a good network of branches. Hopefully next year the tree will have aclimatised to your area and will not open it's blossom so early as to be frosted, although this is variety dependent.  I'm not familiar with US varieties, but hope you have chosen ones that will suit your climate and will fertilise each other.