The taxes aren't double though. A highly simplified example:
1. Your company gives you $1400 to exercise options (I don't think Clearbit is doing this, to be clear)
2. You pay $400 in taxes and early exercise $1000 of options in exchange for 1000 shares at $1 each
3. Later you sell those 1000 shares for $1m total
At step 3, you will pay capital gains tax only on the $999,000 of actual gain. You don't have to pay taxes again on the original $1k.
