Does anyone know why some relic Telecasters have mixed-metal saddle configurations?

[unleashthejay]

Was this a manufacturing approach? The steel saddle was for the low E string and A, and the others were brass. Was this for tone? I know these are relics but I’m curious why.

 

[beaubrummels]

Owners used to swap out some of the saddles for tone. If it's a relic, presumably they are mimicking how a number of old Teles are in their present, relic'd, modified state.

 

[jeremy]

steel saddles tend to be be brighter than brass saddles, so using them on the low strings gives them a bit more snap while using brass on the rest keeps them from being overly zingy