Mouseferatu
Hero
DM'ng and RPG's very nature is subject to individual interpretations.
The problem is, while it's a perfectly valid house rule, it's not an "interpretation." At least not of what's actually written in the book.
Dash is an action, not a multiplier. Take the dash action, move your speed. There is no argument in the RAW for you not being able to dash twice if you can somehow take the action twice. That'd be like ruling the bonus attack offered by TWF doesn't actually occur, because it somehow doesn't "stack" with the main attack.
If dash was written as "when you take the dash action, you double your move," then the non-stacking interpretation would have a leg to stand on. But it's not. It's very specifically written as its own thing. Not a multiplier. Not an addendum. When you take the dash action, you move your movement rate. Heck, while I can't think of a reason why you'd do this, it's possible to move via the dash action and then not use your normal movement at all, in a given round.
Again, house rule? Have at. But it simply isn't a viable interpretation of the RAW, the way they're phrased.