Hi:
Unfortunately, I would say that it is an error on the specs page.
HP Notebook - 15s-du1004tx Product Specifications | HP® Customer Support
The parts list for your notebook indicates that it comes with the Realtek RTL8723DE Wifi adapter.
HP PartSurfer
You could replace the RTL8723DE with the RTL8821CE and have dual band.
You would want this model wifi card, which you can get on eBay or Ali Express, as it is currently on back order from HP.
Realtek RTL8821CE 802.11 ac 1x1 WiFi + Bluetooth 4.2 Combo Adapter (MU-MIMO supported) HP part # L17365-005.
https://www.ebay.com/sch/i.html?_from=R40&_nkw=L17365-005&_sacat=0&_sop=15
The card will have the same 72 MBPS throughput as the RTL8723DE on the 2.4 GHz wifi band, but on the 5.0 GHz wifi band, it will have a max throughput of 433 MBPS when you have an AC router with an excellent wifi signal strength.
Below is the link to the service manual, where you can find the wifi card removal and replacement procedure.
Maintenance and Service Guide HP 15 Laptop PC