xwalk_ags assigns multiple values

[Salvatoredis]

While trying to obtain an appropriate crosswalk, I noticed that for the same counties in 1990, the result provided me with multiple values in 2020.

In my picture, ags1990 refers to counties in 1990, syear is the associated year (1990), and ags20 the corresponding county in 2020. While ag20 should be a single value, I have 2 distinct ones.

[sumtxt]

If 12014 lost territory to both 12061 and 12067 between 1990 and 2020, then this is the expected output. The crosswalk is not a 1-1 best-fit lookup table.