Vengeance was described as a mini-album on first release, as was the 1987 German/US mini-album titled New Model Army.
Do they count as albums? Do any of the anthologies or collections?
Does the Brazilian Adrenaline album count?
I don't count the ones described in record contracts as 'overcall' albums, because they're just releases of leftover material, live recordings and complications, put out by labels to fulfil contractual obligations after a band has left.
EMI released all sorts of material after the contract ended a little early, one studio album short of the five intended. The live album (was it Raw Melody Men?) was counted as a studio album by EMI to complete on the deal, but History, Lost Songs etc. were overcall.
I guess it depends on your terms of reference, be they creative, legal or otherwise.