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Hi, Everyone!!

A: I bought a watch for him.

B: I bought him a watch.

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The two sentences should not be of the same meaning, I guess.

Am I correct?

I guess it is like this.

A: This one means that "I bought a watch, meaning to give it to him, but I haven't given yet"

B: This one means that "I bouht a watch and gave it to him".
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In my opinion, most native speakers use the two forms interchangeably.
I don't find much support for the distinctions you suggest. Only context could make those things clear.

Rgdz, - A.
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Hi,
A: I bought a watch for him.
If you want to get fancy, you could consider a meaning like this.
A wants to buy a watch and give it to B.
A can't go to the store to buy it, so he asks me to go to the store to buy it on his behalf. I do,.
Thus, I bought a watch for him.

Clive
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Comments  
To me, the sentences have the same meaning.
 Avangi's reply was promoted to an answer.
 Clive's reply was promoted to an answer.
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Thanks a lot, Avangi and Clive...

Your answers always make me smile from enlightenment...