I am provisioning a sqlmi instance in azure, and we have 2 subnets created. Primary subnet and secondary subnet(DR). The secondary subnet fails to get created with below error. The records are created also in phpipam. Although the record is added in the ipma but subnet creation failed.

Error: Subnet Name: "sub1"): network.SubnetsClient#CreateOrUpdate: Failure sending request: StatusCode=400 -- Original Error: Code="NetcfgSubnetRangesOverlap" Message="Subnet 'sub1' is not valid because its IP address range overlaps with that of an existing subnet in virtual network 'vnet1'." Details=[]
    
    │   with module.secondarysubnet[0].azurerm_subnet.subnet,
    │   on .terraform/modules/secondarysubnet/main.tf line 23, in resource "azurerm_subnet" "subnet":
    │   23: resource "azurerm_subnet" "subnet" {

Address space: 100.90.69.64/26

How to check the overlap on the subnets/vnets as I am new to networking.