These questions may be appeared in your mind when you hear those words. 'Merge category' is used to combine two category when there seems to be two exact categories of a product in the system, and each of the product has its own transaction records. In this situation you can't delete any of them. So this is what 'merge category' used for, you can merge it into one categories and automatically updating the transaction record by the new categories.
1. Check your products categories, if you have two data categories with same name categories
"products - categories"
2. And for setting merge categories- "Tools - Merge Category"
Input your old category with new name data category "get rid of duplicate name suppliers" then press button Process
3. Done you can get rid of duplicate name category
Note : This 'merge category' tools proccess will be adding the old category's inventory stock and the new one's inventory stock
And also in the report session, it will be the new category which is recorded.