New proficiency not allowing a choice when a duplicate

When already proficient with Arcana and then multi-classing into Cleric and choosing Arcana Domain it should allow you to choose a different skill, as you already have Arcana.

From the PHB section on backgrounds:

If a character would gain the same proficiency from two different sources, he or she can choose a different proficiency of the same kind (skill or tool) instead.

This rule does not say only during character creation or only when choosing a background, so it should apply in all cases.

 So just edit your sheet and get a new prof. 

Problem solved. 

Quote from Cyb3rM1nd >>

 So just edit your sheet and get a new prof. 

Problem solved. 

 Never have a bug fixed with this one simple trick.