This kind of dubbing wasn't exclusive to anime in that era, publishers basically bought the rights to cheap visual content and produced their own stories and scripts on top of it for maximum impact in their respective local markets.
Germany: Die Zwei / The Pesuaders https://en.wikipedia.org/wiki/The_Persuaders!#Redubbed_versi...
Most famous and polarizing was probably the reworking of three different original programmes (Macross, Southern Cross and MOSPEADA) into Robotech
Earliest example might have been https://en.wikipedia.org/wiki/What%27s_Up,_Tiger_Lily%3F
but the french perfected this sub-genre in the 70s:
http://physicalimpossibility.com/2011/05/22/movie-rip-offs-a...