Why is a second iPhone showing up during calls on my device?

Your 2 devices are using the same Apple Account and you may have WiFi calling enabled on the iPad. There is nothing wrong with this set up and you can continue the conversation on your iPad if you wish. Review the information provided here about how call forwarding works to allow calls on the iPad along with Hand Off to continue the conversation on the other device.

Use iPhone to allow calls and text messages on your iPad - Apple Support

As lobsterghost1 said, the reason why you see the name iPhone is because that is the name you have listed for that device as seen at Settings > General > About > Name. You probably used your iPhone backup when setting up the iPad. It is the name of the devices shown in your screenshot, not what type of device it is. That is indicated by the icon next to the name.

On your iPad, open Settings > General > About > Name. Is it by chance listed as a phone? You can change the name there to something like Mary's iPad.

Pipengineer123 wrote:

meaning the iPad is listed as a iPhone. But it wasn’t around when I got the call.

If you have Wi-Fi calling enabled the iPad doesn’t have to be around.

When viewing the devices listed at https://account.apple.com , how many iPhone devices are associated with the Apple Account?