Shapepoint calendar category issues

[AndreaG729]

Hello Im am new to Sharepoint and I am having an issue making a calendar (that will need to be added to Teams). 

I have created new categories and have no problems as well as the overlay colors.

My issue is when I create a new event and select a category and save it, automatically adds another one and puts it in as different category. Im not sure what to do or if there is a box that can be unchecked to not make duplicates?

EX: I created a Due date event and put it as a red category. when I look at the calendar it show the Red Category and a green one was automatically created... I dont want the green one. 

In the image I tried it with two different category and both auto created the green one each. 

Can someone explain how to fix this 

[#2]

@AndreaG729 

Have you just added the same overlay twice? Did you add another SharePoint calendar as an overlay or an Exchange calendar? 

Overlays are essentially different calendars so you cannot categorize events in one calendar to show in different colours. 

[#3]

@Andrew Hodges No. I made sure to go and delete the calendar from the Sharepoint site, i was thinking that as well so I did try (unless you have to go in some other way to delete the categories)  I even started a new one on a different sharepoint site and it still is happening