Apache virtualhost is redirecting to the wrong virtualhost

Configuration error?

First of all, your example1.conf file does not contain a closing </VirtualHost> tag. Since this file gets loaded before example2.conf the second domain probably does not get loaded correctly. Do you get any errors when reloading Apache? You can use mod_info to verify both virtual hosts are loaded correctly.

Domain Name System

I do not fully understand your remarks about DNS. You mention "IP address of the older site" as if the new site has a different IP address? As your same virtual machine (droplet) hosts both websites, all names should point towards this one IP address of the virtual machine, either directly (A record) or indirectly (CNAME record).

For example:

example1.io.        A       203.0.113.80
www.example1.io.    CNAME   example1.io

example2.com.       A       203.0.113.80
www.example2.com.   A       203.0.113.80

You can test and verify all the names point to the same IP address by using ping or dig from a command-line interface.

HTTPS

What does your 000-default-le-ssl.conf file looks like as you redirect example1.io to HTTPS. Are you testing example2.com via HTTP or HTTPS?

Logs

When you visit http://www.example2.com/ and you are presented with the web page of example1.io, what do you logs show?