Compare 2 fields value & set another field with unique values

Lokesh_2sqoy1

Is there a way to set a field with only unique values from 2 fields

Field 1 (Single select)

Field 2 (Multi select)

Field 3 (Text multi-line)

Use cases & expected results

• Field 1 = A, Field 2 = A,B, Field 3 = A,B
• Field 1 = B, Field 2 = B,A, Field = B,A
• Field 1 = A, Field 2 = B,D,A,C, Field 3 = B,D,A,C
• Field 1 = A, Field 2 = B, Field 3 = A,B

Any ideas much appreciated.