The ace lead creates a new ambiguity - is it from A-K-x or A-x-x? - but this is theoretically less common since players often avoid leading an unsupported ace at trick one.
If playing Ace from Ace-King, you should lead the king from an A-K doubleton. (This is the opposite of standard leads, in which the ace is led.) Leading the king followed by the ace tells partner that you have a doubleton (and may be able to ruff the third round of the suit).
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