It's not an animation issue, unless the animation only happens when "Melee"/Charge radius has been reached.
As for the double clicking/running... they still stop. They will run to their target, get to charge distance, stop, switch weapons, then attempt to charge.
Try it yourself. It's very silly.
No archers, I'm not telling you to run at the enemy so you can bash them with your bows... but if you could do that without having to stop I'd gladly let you.
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