thx.
Basically, it's "normal" but not really great for you.
More about downside protection for the VC, so they can cut their losses.
Also as you reach these milestones, your company should be worth more (since you created value), but by doing this the VC sets the price for the future milestone based investment tranches at the lowest price (zero milestones reached).
They have also mentioned 'redemption' and 2x preferred stock - both of which kind of ring bells.
The right answer is probably "We're negotiating our first round of funding right now. We'll negotiate our second round of funding later."