Kakashi did use Tajuu Kage Bunshin(on the kanabi bridge in part1) [
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]. The Bunshin no jutsu and Kage Bunshin no jutsu have different handseals. The Bunshin no jutsu's handseal(clone technique) is Ram → Snake → Tiger
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The Kage Bunshin no jutsu's handseals however has a particular clone seal [
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]. And it's that seal that Kakashi used after the battle against Zabuza(Bottom left panel is the same as Naruto's as well)[
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]
Secondly why would he say Kage Bunshin if he used a normal Bunshin technique?
Thirdly it's also said in the databook that Kakashi used a tajuu kage bunshin at that point in time. The only question you must ask yourself is why is he capable of doing that and you can only ask that when you don't understand the working of the technique