No,
Once I am satisfied they have no nasties in their system I see no problem. Though if any of them become ill etc they will be qt'd until I am sure there is no risk of cross infection. It's all down to how you quantify the risks - when you know there will shortly be interaction such as breeding then you simply reassess the animals beforehand.
I don't add many animals to my collection on the whole so rarely encounter the scenario of multiple animals in qt from different sources and times. For those situations the qt time resets for all animals when a new one is added.
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