I have purchase data:
2 Eiger Starter Daypack 16L Blue, purchased on 2 July 2023
2 Eiger Starter Daypack 16L Olive, purchased on 2 July 2023
2 Eiger Starter Daypack 16L Blue, purchased on 3 July 2023

I want automatic formula in my sales data :
If, 1 Eiger Starter Daypack 16L Blue sold on 5 July 2023, the purchase date will be shown 2 July 2023
1 Eiger Starter Daypack 16L Blue sold on 6 July 2023, the purchase date will be shown 2 July 2023

but
If, 2 Eiger Starter Daypack 16L Blue sold from 1 buyer on 5 July 2023, the purchase date will be shown 2 July 2023
1 Eiger Starter Daypack 16L Blue sold from 1 buyer on 5 July 2023, the purchase date will be shown 3 July 2023

Kindly help.
Thank you.