I am sure I'm missing something obvious, and apologies if...

I am sure I'm missing something obvious, and apologies if someone has explained it before. How can POSCO take their holding up to 19.9% in tranche 2, if they already hold that in tranche 1.

POSCO signed a binding agreement for a US$40m equity investment in Black Rock, which
is expected to take place via two tranches:
– Tranche 1: A$9.0m investment in 155.3m shares at a price of A5.8c, a 10% premium
to the 10-day volume weighted average price, increasing POSCO’s stake in Black
Rock from 10.1% to 19.99%
– Tranche 2: The balance of POSCO’s US$40m investment will be at the same price
as other investors in the final equity raising to build Module 1 on the Final
Investment Decision (FID), capped at a maximum stake in Black Rock of 19.99%