Food can be reheated twice.
Just be careful to not heat it up too much or you might burn the food.
When you reheat food more than once it can become burned or overcooked depending on the type of food you have.
Food can safely be reheated twice or even multiple times but the more you reheat the food the quality of the food decreases each time you reheat the food.
So you want to avoid reheating food too much.
However reheating food twice should not degrade the quality of the leftover food too much.
I've reheated food twice before and it's been okay.