I'm not sure this rule is necessary and the line for enforcing what can and can't be considered too similar seems as blurry as the existing line of what factions should and shouldn't be approved.
Also, it doesn't seem to be a problem when, for example, Nashoba has approved my submissions or vice versa, but this rule would block that. So I'm not sure I'm feeling it.
I'll be listening to the feedback in this discussion.
Also, in the future please don't use a Setting Submission template to start a setting discussion.