Can I have two VPC with same subnet (both VPC are in different project).

Question

Can I have two VPCs with the same subnet? (Note both VPC are in different projects).

Answer 1

(VPC is typically an AWS term. Azure uses Virtual Network, often shortened to vnet)

You can have 2 Virtual Networks that contain 2 different subnets with the same name.

You cannot have 2 Virtual Networks that share the same subnet. A subnet is a child resource to a Virtual Network, and the subnet can only have 1 parent.

A typical design where two Virtual Networks need to be connected, is to use Virtual Network peering. This is where a connection is made between the two virtual networks.

A more complex design would involve a hub-spoke architecture, where a central hub provides shared resources (firewall, on-prem connectivity, etc) as illustrated in the diagram below.