I think I see what’s going on here.
You have two transactions with the same triplet of (TXID, symbol, and address).
Normally there is a unique constraint on these columns on the DB. The constraint’s name is uq_tx_idx.
It’s possible that you are missing this constraint, if you transferred the database via export/import.
What I find strange is that normally the plugin would warn you about this in the admin screens. Did you ever see such a notice in the admin screens?
Can you please go to your MySQL console and type the following?
SHOW CREATE TABLE wp_wallets_txs;
The indices on the table should look like this:
PRIMARY KEY (id),
UNIQUE KEY uq_tx_idx (txid,address,symbol),
KEY account_idx (account),
KEY blogid_idx (blog_id)
Let me know. Thank you.