Protest The Hero with Kezia and Fortress. I find this one interesting as I truly feel both these albums are 10/10, but they're much outside of my usual style choice.

Full on 10/10, meaning every song is 5-star, all songs on the album are 'perfect'?
Very few albums for me hit that level, and only 2 bands have 2 albums which I would truly consider "perfect"

For Metalstorm, I simply round. Anything that is 9.6 or higher gets rounded up to 10 for me here, so the numbers are notably different.

"full" 10/10 albums (including "temporary" 10/10s from the last 2 years, these may fall off if they don't have staying power):
Queensrÿche - Operation: Mindcrime
King Diamond - Abigail
Voivod - Dimension Hatröss
Mastodon - Crack the Skye
Candlemass - Nightfall
Judas Priest - Painkiller
Iron Maiden - Powerslave
Immolation - Close to a World Below
Dissection - Storm of the Light's Bane
Lykathea Aflame - Elvenefris
Caladan Brood - Echoes of Battle
System of a Down - Toxicity
Cryptopsy - None So Vile
Nile - Annihilation of the Wicked
Demilich - Nespithe
Svartidauoi - Flesh Cathedral
Oranssi Pazuzu - Mestarin kynsi
Thorns - Thorns
Ethereal Shroud - Trisagion

For me, the only bands on the list with a 2nd 10 is Candlemass (Epicus Doomicus Metallicus) and Voivod (Killing Technology)

tons of close ones though, off the top of my head
DsO - Fas, Cirumspice, and Paraceltus
Slayer - Show No Mercy through Seasons
Immolation - Failures through Unholy Cult, M&D, Atonement
Mercyful Fate - Melissa and DBtO
Faith No More - Angel Dust and King for a Day

Basically I can only think of Neurosis and Blut Aus Nord for this. There's some one album projects maybe like Lurker Of Chalice. But it's extraordinarily rare for me, like 10s in general.

Not metal, but the shoegaze band Whirr has two 10/10's for me too. Sway and Feels Like You are two phenomenal records.

Recently, I've limited giving out 10s only to "elite" albums that I completely love and where practically every song is perfect. They usually tend to be some of the first metal albums that I truly adored which probably makes it a bit more biased, since: I physically own most of them on CD and I've had a longer time to listen to them. Newer albums that I discover won't get a 10 - only if I've listened to it a lot and know for sure that I'll always love it.
Right now, I have 19 studio albums and 1 compilation that get a 10/10 rating. Of those, the band's with multiple 10/10 albums are:
1. Judas Priest (Painkiller + Defenders of the Faith + Essential Judas Priest [Compilation])
2. Death (Spiritual Healing + Symbolic)
3. Megadeth (Rust in Peace + Peace Sells...but Who's Buying?)
4. Slayer (Seasons in the Abyss + Show No Mercy)

Personally I don't consider that every track has to be perfect for the album to warrant a 10/10.

Some albums have so many amazing, memorable and influential tracks that it elevates the album above the rest. I also think it has to pass the test of time. I'd never give an album released in the past 1 or 2 years a 10 but that's not to say it shouldn't be given 10 in the future.

So Maiden, Priest, Metallica, Slayer, Voivod, Kreator, Sepultura, Death, Suffocation, Nile, Dissection, Opeth and Mastodon for me.
Megadeth only have one.
Celtic Frost only have one if you consider MT an EP.
Bathory have several 9's but I can't give a 10 to any of them.
Morbid Angel also have several 9's.

Mine are:

Metallica
'Master Of Puppets', 'Ride The Lightning', '...And Justice For All' and 'Metallica'
Just a string of fantastic albums as I'm sure most metalheads would agree (the top 200 certainly would suggest so, minus the black album of course).

Opeth
'Blackwater Park', 'Still Life' and 'Ghost Reveries'
Again, another popular one. Just fantastic prog.

Iron Maiden
'Seventh Son Of A Seventh Son' and 'Powerslave'
Number of the Beast is a great album also, but not worthy of a 10 IMO, unlike these two.

Wintersun
'Wintersun' and 'Time I'
Fantastic, skillful, creative, epic metal. Both albums are top notch IMO. The Forest Seasons is a disappointment though.

Trivium
'Shogun' and 'Ascendancy'
A lot of personal bias in this one as Trivium were the band that got me into metal and inspired me to pick up the guitar and start making music of my own.