Yes, you can use same GST number for any number of business lines within a state.
However there is option to obtain registration for different verticals.
Even if business is different from current business, it is advised to run it with single registration to avoid much compliance related complexities.
However, final decision should be made based on cons and pros of single vs double registration related to your business.
But to answer your question, yes you can do multiple different businesses with same GST registration.
chatCommentsThanks for your clarifications.... - Day 2Day