Basically if you wanted to sell the older stock you should have done so in the broker account where they were housed. Since you sold the newer stock in the robinhood account then that is what will be reported to the IRS.
The IRS will not compare your purchases with your sales if that is what you think ... they rely on the broker to report the sale on the 1099-B and that is what they go off of. If you choose to change what the broker sends to the IRS then be prepared to prove your entries if the IRS audits you.
