There's one possibility that I can think of: the text of TC leaders is an attribute. If they're still identified as leader dimensions or whatever when they're imported, you can select all copies of each by attribute, ie the text or dimension of original and copies of one leader (looks like "non vehicular line" or similar for one of those in your snip, that's the attribute), deselect the one you want to keep and delete the others. If they're stripped of their attributes or have their object type deprecated, I think you'll be doing it manually.
I just noticed that the copies seem to have differently-coloured text. If that's the case, it might be possible to select the copies by query, the query I tried is 'Object type'='Leader Dimension' AND '[Leader Dimension]Text color'='Red'