Based on this thread and other similars these are the items that can somehow duplicate in the inventory and from what action:

• Weapon: Vordr's Bite - Equipment Chest drop + Legendary Animal reward
• Weapon: Mark of Sol - Can be purchased from General Shop multiple times at Settlement 6
• Shield: Raven Clan Shield - No idea how to reproduce
• Armor: Galloglach armour - Dupes when turning in Vegvisir Scheme (Front) from General Shop
• Armor: Huntsman armor - Dupes when turning in Muninn Call Scheme (Front) or Mjolnir scheme (Front) from General Shop
• Tattoo: Odin's Emblem tattoo - Dupes randomly when picking up Flying papers
• Ship: Asgard Tailpiece/Shields - (Not 100% sure) Probably dupes from one of the Fishing/Hunting delivery
• Jomsviking: Raven Clan Breeches - No idea how to reproduce (bronze rarity 2x)

At this point i don't want to play the game anymore just to avoid save rollbacks when something dupes ... I tried to avoid all the Flying Papers, the legendary animal, the hunting/fishing deliveries, but it seems like it's not the only source so I guess i'll just wait until the patch ...

Did i missed anything from the list?

1 months, 2 bit patches since release ... 1.0.4 didn't fixed this, and nor do 1.1.0

The issue is still there i can still repro the item dupe with f.e. the Muninn Call Scheme (Front), and still have the dupes in the inventory / jomsviking's inventroy ... but the worst offender is that it's been reported multiple times with repro steps and it's still not even in the Known bugs thread ...

From 1.0.4:

Removed duplicate gear from inventory.

Now this part of the patch totally failed.
Tried two different saves:

• All previous dupes are still there from my last save (saved in1.0.2) when loading up the 1.0.4
• I can still repro the duping by turning in the problematic tattoos (f.e. Muninn Call Scheme) on the new 1.0.4 patch

Thanks to multiple duplicated items issues i went to check on my tattoos and found another bug that first i thought might be another duplicate problem, but instead it's just a text error.

The Auki Sign Schemes are from Flying Papers and those are unlocking the proper Auki Sign tattoos, but there's a different set of Auki Sign Schemes sold by the Mechants.
Those from the Mechant use the wrong names and instead of Auki Sign tattoos those are unlocking the Dupuytren tattoos and shold use the Dupuytren Scheme (...) name.

Repro:

• Buy any Auki Sign Schemes from Mechant
• Turn them in at the Tattoo Shop
• Unlocks the related Dupuytren tattoo

Fix:

• Rename the Auki Sign Schemes sold by the Merchant to Dupuytren Schemes

Version: 1.0.2

Based on this thread and other similars these are the items that can somehow duplicate in the inventory and from what action:

• Weapon: Vordr's Bite - Equipment Chest drop + Legendary Animal reward
• Weapon: Mark of Sol - Can be purchased from General Shop multiple times at Settlement 6
• Shield: Raven Clan Shield - No idea how to reproduce
• Armor: Galloglach armour - Dupes when turning in Vegvisir Scheme (Front) from General Shop
• Armor: Huntsman armor - Dupes when turning in Muninn Call Scheme (Front) or Mjolnir scheme (Front) from General Shop
• Tattoo: Odin's Emblem tattoo - Dupes randomly when picking up Flying papers
• Ship: Asgard Tailpiece/Shields - (Not 100% sure) Probably dupes from one of the Fishing/Hunting delivery
• Jomsviking: Raven Clan Breeches - No idea how to reproduce (bronze rarity 2x)

At this point i don't want to play the game anymore just to avoid save rollbacks when something dupes ... I tried to avoid all the Flying Papers, the legendary animal, the hunting/fishing deliveries, but it seems like it's not the only source so I guess i'll just wait until the patch ...

Did i missed anything from the list?