Greetings,
I know D&D 5e makes Dash a pure action as such instead of the former option to convert the Attack action into a second Move. But, in practice, the later does not alter the rules or affect gameplay nor game balance, yet gives the players a bit more flexibility if they realize one Move was not enough (sacrificing their Attack to do a second Move).
I see no reason not to allow it, as it does not affect anything else.
( Unlike Evade, which is a particular action that does affect gameplay. )
ps: the current animation for Dash looks like a spell and that is not really immersive for me. Suggestion: a sprinting-like body language would be fine for double-move/Dash.
