Lone Star (a UFO spin-off)
Diamond Reo
Armageddon (two 70's bands)
Skid Row (Gary Moore)
FM (a great Canadian prog band)
(The) Sword...if they count?
Black Cat Bones
The Gods(Z) two 60's psych bands

I'm not sure anyone would have heard of the original Iron Maiden if "our" Iron Maiden hadn't become famous...but the other Iron Maiden was a pretty good heavy psych band.

Many, many more. I'll think of them if you don't.

Ultimatum. great 80's female fronted metal band.

Their was a band named Nirvana in the 60's and their were two Hellion in the 80's.

there was a british punk band called Anthrax.

There was a west coast version of Overkill

Then you've got the whole Wrathchild (british glam crap band) vs Wrathchild (America) fiasco.

I vaguely remember Megadeth being sued by a no-name band called "Megadeath" (with the "a" in "death") years back ... but they'd never recorded anything under the "Megadeath" name so the case was thrown out

Deliverance - at least 5 bands named that

Iron Maiden - An English prog rock band released 1 album in 1975 (I think).

Nocturnal Tights

A band I saw play at a bar in Greece. Laughed my ass off when I read their poster!

I believe that there are 2 Warrants. The hair metal band and a thrash band.

Yeah, and there were different Slayer, Poison and Steeler too

2 Skid Rows, one with Phil Lynott :metal: , and the other with Sebastian Bach.

These are all bands I like a lot:

Titanic (early 70's HR from Norway)
Goliath (70's Hard rock)
Epitaph (a German Prog band)
Strife (Uk sorta like Hawkwind)
Pirates (SF)
Fandango (two, both with Deep Purple connections)
Airborne (70's AOR band Beau Hill)
Dakota
Gomorrah (a psych band with some Christian themes)
Touch (one psych one AOR)
Banchee (the one you guys mention is spelled Banshee, but still confusing)
Gun (the 60's band liked to call themselves The Gun, but it never caught on)
Megaton
Savage Grace (70's hard rock)

I think the two Jerusalems, Fists, and Deliverances were fairly simultanious with each other, but from different places. Deliverance UK was an very anti-Christian band ironically. There was a doomish Serenity in the mid 90's, pretty good really. There were two very similat AOR bands around 1980, Spy and SPYS. And then there is Mastadon and Mastodon.
For some reason I think there have been multiple Frosts, Warlords, Andromedas, and Leviathans, but I'm not sure about those.
There have been a couple of prog bands called Cathedral, but I've never heard them. And to really stretch it, there was Bad Seed from the 90's. A stoner/doom band that had nothing to do with Nick Cave, but did sound a little like Penance.

Wargasm was orginally called Overkill. Saint Vitus was Tyrant and I believe there have been other bands called that.

There is at least two Overkills.

The was one other Mortification.

There are a bunch of Warfare and Pariah. Including one Pariah that is an easy listening soft rock group. The best on itunes is some guy going off because he accidently bought it thinking it was the former Satan/Blind Fury.

I looked Raven on Amazon and this is what the results came up with: