Old Bug, experienced this for at least a year or so with the official roll20 5e character sheet, took a hiatus before resuming activities, and the same issue persisted. When a character sheet from a vault is imported, whether by GM or players, there's a small chance that it creates two copies of the sheet. Each of the two sheets hold shared control, as in, changes in one affect the other, including removal; meaning that deletion of either sheet prompts the removal of the other. Once this occurs, the bug tends to continue with further importations of the particular sheet, prompting either a complete sheet remake from scratch or duplication of a game to resolve the bug. Cheers & Stay Safe, -Zu