search one column containing text and return first value of each type in adjacent column

I have a series of text values in one column with most values appearing multiple times. I want to search that column (col B in below sample) and return one of each textI value in an adjacent column (col C sample results). I also want no empty cells in the adjacent column. A sample of the contents is below. I can't use a macro to do this.

Col B Col C
DI-NL DI-NL
DI-CX DI-CX
DI-MO DI-MO
DI-MO DI-PS
DI-PS DI-RS
DI-RS DI-AD
DI-MO DI-RR
DI-PS AF
DI-AD
DI-RR
DI-AD
AF
DI-RR
DI-UR
AO-NQ
DI-NQ

With your source list in B2:B17
and
C1: any heading that is not a listed value...MyList

This regular formula begins the list of unique values, in the order encountered

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Copy that formula down as far as you need.

Is that something you an work with?

in cell C2, and drag-fill down:

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make sure that C1 has a value that DOES NOT appear in the list in column B.