Retaining old object field in add fields

[burkekevinm]

When you use add fields and switch objects in the same window it's retaining the previous selections.

Steps to reproduce:

Open a new query tab
Select an object and click add fields and select a field (ex. Contact > CreatedDate)
Execute a query
In the same tab change the record to another object (ex. Account)
Clear the existing query
Click on add fields and select a field (ex. Name)
Click add

The query will include the previous selected field (ex. CreatedDate) as well as the new field (ex. Name)