Ansible: What is the variable order/precedence in case of multiple 'extra_vars' files?

Question

In this older question about "Can extra_vars receive multiple files?", the original poster answered the question, saying that multiple vars files could be accomplished by just using multiple --extra-vars parameters.

The followup question that I have is that, in such a case, where the ansible-playbook command line has two --extra-vars parameters, each pointing to a different file, what is the order or precedence of those files?

Also, what happens if both files have the same var name (e.g., my_host) in them?

For example, say I have 2 files, extraVars1.yml and extraVars2.yml and in the ansible-playbook command line I have:

ansible-playbook... --extra-vars "@extraVars1.yml" --extra-vars "@extraVars2.yml"

and the extraVars1.yml file has:

my_host: 1.2.3.4

and the extraVars2.yml file has:

my_host: 5.6.7.8

What will the value of the my_host var be when the playbook is run?

Thanks! Jim