Yes you can freeze milk twice or even more than a couple times.
Milk can be frozen multiple times without any harm to your health from the milk.
However the more you freeze milk the worse it may taste.
Frozen milk tends to taste different than fresh milk so you may or may not like the taste of frozen milk.
Freezing milk is okay to do to preserve the milk and make the milk last longer.
However in my own opinion freezing milk is not a good idea because when you do freeze the milk the milk changes in tastes.
Some people don't mind the taste of frozen milk but other people including myself find frozen milk disgusting tasting.
I once decided to freeze some milk and then thaw it later but hated the taste and will no longer freeze milk.
I just buy milk when needed and use the milk up before it has a chance to go bad.
Frozen milk will not harm you but frozen milk tastes a lot different than fresh milk.
When you freeze milk the frozen milk should last for up to 6 months.
When thawing frozen milk make sure to thaw the frozen milk overnight in the refrigerator.