Here's the scenario. 2P Hub any%, (Both players would be recording their gameplay for proof of no shenaningans for this scenario)

Both start from new character and you accept the DLC and enter the hub, but before you do anything you dupe gunpowder to make access to more bombs a thing during the run. Each dupe takes around 2-3 mins real time but no run before has done this, so I wanted to ask if it would be allowed and wanted to ask the mods.

All runs must be done from a fresh files and timing begins at the start of creating a file. This is why Hunter cards are shown in the VOD so no additional quests are done by any of the players before the run starts to give a unfair advantage in preparing resources or a file. Showing the cards should show that all quests are at 0 and playtime and weapon usage is also 0 to show this, or if this is done at the end of the quest, the quests done should mirror your own card to show everyone has been doing the exact same quests and no additional things have be done to a person's file.

The way the runs for co-op work is that all runs need to be done in unison. otherwise you could junk 2 players and just ignore 2 of the HR3 promotion quests and go for the repel quest for a "time save". or in what you are suggesting having a unfair advantage of resources. Anyone who does quests extra is essentially invalidating a run for the group.

But if you wanted to dupe things and what not for a run as a group, then by all means feel free too. but the timer would be going from file creation and there wouldn't be anything other than time cost on your end. Cause again, all quests need to be done by the group. and not just a random person going off and doing their own thing then coming back. But that doesn't stop the group of going and doing quests together in a route in duping items or resources. Just remember the guild cards should all be shown in the VOD still to show no additional quests were done by a party member and all files were made at the same time to help a mod to validate a run. (can be done after time if you want to save time)

Shauny pretty much got it all down. If you want to dupe items then go wild, I see no issues with it as long as we for sure know that both characters were made together and are both participating in the run.