Warn Users When Possibly Submitting a Duplicate Combo

[GordonsKitchen]

We frequently get combo submissions which are either duplicates of pre-existing combos, or are pre-existing combos that the user has added additional cards to (payoffs). It would be good if the submission form could help weed these out. I imagine this working out the following way:

1. User submits a combo that is either a direct duplicate, or a duplicate with added cards. Let's use Sliver Queen + Mana Echoes + Parallel Lives as an example.
2. Once user goes to submit, they are given a page. The page says something to the effect of "The combo you are trying to submit may be a duplicate of a pre-existing combo, or may contain a pre-existing combo. Please check the information below and ensure your combo is not a duplicate, and meets our submission guidelines".
3. Below the warning, there can be links to the combo(s) it may be a duplicate of (in this case, Sliver Queen + Mana Echoes). Below that can be a list that the editors can give you about payoff cards so the user can make sure their combo doesn't contain them, and needs the cards that are listed. This would contain things like "We only accept combos in their simplest form, and without any unnecessary card".
4. After all that, the user can be prompted with two options. First, to submit the combo as normal. There it will go to the backend as normal for an editor to review. Second, they can go back to the submission form with the passed information to change it into a unique variant.

I do understand that the current backend does not enforce real card names being passed into the cards field. I would just search it as passed by the user. This is just meant to (hopefully) catch most of these before the editors have to review and deny them manually, and create a bunch of bad variants behind the scenes. Another concern could be the number of checks that need to be done to check all the combinations. If it helps, we could only do this check for combos with 5 or less cards. 6+ card combos are rare and we can weed those manually.

Example of what I'd want to weed out:

This is a payoff variant of https://commanderspellbook.com/combo/2440-4385/.

[GordonsKitchen]

These three were submitted all after each other, and could have probably been avoided with this change