I believe there may be a bug with how transactions are handled from Fidelity Investments brokerage accounts. After observing my own feed for a number of months, it appears that whenever a transaction occurs on a stock market holiday, Fidelity posts a pending transaction. Then, the final transaction is posted on the next business day.
The apparently pending transaction and the final posted transaction, which occur on different dates, both come through the feed, resulting in duplicate transactions but with different dates.
If you go back and look at the detail on the Fidelity side, there is only one transaction at any given time— either the pending or the final—depending on whether you check during the weekend/holiday or business hours.
Is this something which could be addressed with Yodlee and/or Fidelity? It can become difficult to match up transactions, particularly if one is using the Fidelity debit card in addition, often for the same transaction amounts, and especially if using overdraft protection to feed funds from an investment to cash management account.