If the display settings for an item model would cause it to stretch across multiple GUI slots, it will instead stay contained within one slot but have parts of its model added to other items in your inventory. Attached resource pack applies a model to sticks demonstrating the issue.
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duplicates 1
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Looks like that is describing the same issue, guess I didn’t search well enough before submitting. Not sure why that one would be labeled invalid, though.
Is this any different from MC-296431?