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Hard to tell from the pic, but from personal experience, clones are much more fragile than seedlings of the same size. You'll have to play it by ear and watch for any signs of burning.
I think you're probably at around a good height for now, if they're not showing any signs of burns that is. Slowly lower during a week or so.
You'll simply have to keep monitoring them and raise the lamp quickly if they begin protesting.

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