Why does a (2) appear next my iPhone on my account?

The simple answer is that there is more than one phone shared with Find My that have the same name, so it adds a suffix to differentiate the phones. And the solution is to go to Settings/About/Name and make each phone’s name unique. It can be anything you want; for example, my phone’s name is Don’tPanic.

Bobby9681 Said:

"Devices: What are the only reasons a (2) would appear next to one of my iPhones on my account?"

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Have you Renamed this, Ever?

One common reason is because one has renamed this device twice. See here: Change the name of your iPhone - Apple Support

Bobby9681 Said:

"Devices: […]I’m not rally tech savvy but want to make sure that it isn’t an intimation that he has two phone or something like that?“

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Verifying this Device:

Select it in your Device List, and see if it has the same Serial Number. If so, then it is the same device. Being this is an account issue, I recommend calling, having them sort out this “(2)”. Here is their contact info:

Contact Apple Support:

Being that you think your account has been hacked, perform the above, and contact Apple Support, ASAP. They'll run you through the fix.

Apple Support Contact Us Info:

• Contact Us - Choose Locations
• Proceed from there, as necessary
• Why the Wait: Phone calls are taking a bit to go through at the moment, due to lots of calls. With the Coronavirus Pandemic, many are at home at the moment, with much time on their hands to contact Apple. So, just stay on the line, and you will get through :)