In column A, I have a unique value. In column B, I have a series of
additional values which are keyed to match the unique value in column
A. Here is an example of what I have:

COLUMN A COLUMN B
RDK3173BK 14542 , 14567 , 16763
WSK3173AK 14644 , 16688 , 16789 , 16821
PCK3MOP 14638 , 16637 , 16815 , 14639 , 16638 , 16816

I need to convert the series of values in Column B to individual rows
that still match Column A. Like this:

COLUMN A COLUMN B
RDK3173BK 14542
RDK3173BK 14567
RDK3173BK 16763
WSK3173AK 14644
WSK3173AK 16688
WSK3173AK 16789
WSK3173AK 16821
PCK3MOP 14638
PCK3MOP 16637
PCK3MOP 16815
PCK3MOP 14639
PCK3MOP 16638
PCK3MOP 16816