How to merge multiselect options if I have same option twice?

I have same multiselect option many time this happens when I imported Airtable base to Seatable through script.

The options are like this:

And when I use group by the that it shows separate groups for that.

But when I manually correct it and make only one option for same option in multiple select and manually corrected them.

Then also it is showing same groups like earlier.

I am unable to share more than one screenshot that will try to share in comment.
Any solution?

In group by it shows like this: