1970 WHITE PLAINS CD: Same frequency with 4 different call signs?

[Archie]

Why would their one CD frequency of 158.955 have four different call signs assigned to it ? Came to mind after seeing a 1970 CRB Research NY listing.

 

[nd5y]

Probably four different stations with different licenses on the same frequency. There is nothing unusual about that.

 

[GTR8000]

Different fixed locations (base stations). Back in the day, it was common to have one license per site for the same frequency. Nowadays it's more common to have up to 6 sites on a single license. The licensing rules have changed throughout the years.