Is it possible to use the same hashtags on other campaigns?

You cannot use the exact same hashtags for the same campaign period, on the same social media channel, in the same country.

It is possible to use the same 2 (or some) hashtags at most though (as per the example below) but it is recommended not to:

Example: Campaign A ＃Hashtag1, #Hashtag2, #Hashtag3

Campaign B ＃Hashtag1, #Hashtag2, #Hashtag4　→OK ＃Hashtag1, #Hashtag2, #Hashtag3, #Hashtag4　→× NOT OK

Basically, you can understand that the group of hashtag in the second campaign cannot include ALL hashtags in the first campaign

It can be included some AND other different hashtag(s).