There might be minor bug in option trader app.
I have both Dhan and Option Traders apps installed on my device. Instead of 2 notifications I am getting total 3 notifications for everything (any news, market hour update, pre open, market close update, fii and dii buy-sell, etc).
Dhan app - 1 notification (working fine)
Option Trader - 2 same notifications (bug)
Total 3 notifications.