No. Ethernet and Wifi cannot have same IP address. We understand this with an example. Let us assume that you have a laptop which is connected to your Wifi router. The laptop has an ethernet card and a wifi card.
The ethernet port is connected to the physical port on the router using an ethernet cable and the wifi card is connected to the wifi router using the wireless link.
The Wifi router is configured with a DHCP server which is used to provide dynamic IP address to users on the network. In this case, both the wifi card and the ethernet port would recieve an IP address automatically. These would be two different IP addresses.
This is because the wifi router is getting DHCP requests from two adapters. It is not aware that these are from a unique system. Each adapter has a unique mac-address for which unique IP address would be allocated.
If both the adapters have the same IP address , it can cause duplicate IP address issue and communication would not work.
So when using ethernet and wifi on the same system, the IP address on both the adapters have to be different.
CanI configure static IP address which are same for both the adapters
No. You cannot. Every system on a network should have a unique IP address. If same IP address is configured or detected, it would cause duplicate IP address issues.
My ethernet port and wifi cards are connected to two different wifi routers. In this case, would same IP address create a problem
No. It will not create a problem because they are now on different networks as opposed to scenario 1 where they were on the same network. So you can have the same IP address configured in this case.