Hello Mahmoud Qazait
Welcome to Microsoft Q&A Platform, thanks for posting your query here.
Yes, you can apply an existing or future Reserved Virtual Machine Instance (RI) to two VMs running at the same time for 300 hours each. The RI will be applied to the VMs based on the size and location of the VMs. The RI discount will be applied to the cost of the VMs, reducing the overall cost of running the VMs.
When you purchase an Azure reservation, you are essentially pre-paying for a certain amount of compute usage, which can then be applied to your VMs as a discount. The amount of discount you receive depends on the size and configuration of the VMs and the type of reservation you purchase.
For example, if you purchase an Azure reservation for 300 hours for a specific size and configuration of VM, you can use that reservation to cover two VMs running at the same time for 300 hours each. In this case, both VMs would receive the discount from the reservation.
Refer these documents for more details:
https://learn.microsoft.com/en-us/azure/virtual-machines/capacity-reservation-overview
Hope this helps.
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