Field names changes in UAT environment

Hello everyone, I have encountered this problem after I exported the solution from Dev environment to Uat. There a field in the opportunity form that named "Stay", which was named "object" before until we changed it to Stay. However, when I exported the solution to Uat, the field appears as 'object' on the form.

I have checked that the display name and the label (the checkbox has been checked for the appearance on the form) are both "stay" in Dev and Uat environment. 

Did anybody has ever had this kind of problem before?

Thanks a lot!