1898 and 1904 Sanford Fire maps list as "Mostello"
Broad Street: 1911
1911 Sanford Fire map reads "Broad (Mostello)."
The reasoning is clear when you look back at the 1898 map; at that time S. Main is listed as 45’ wide, while Mostello is listed as 105’ wide (though there is a well and horse shed in that span).
Mostello Street: 1922
1922 Sanford Fire map reads "Mostello (Broad)." Maybe the name Broad didn’t stick?