Connection with Wrong hostkey

I Am using Winscp 4.3.9 for SFTP my files Using SSIS package.Its working fine.
we are using the following command to connect to winscp in my script

open sftp://user:password@example.com -hostkey="ssh-rsa 1024 xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xX"

But recently for testing purpose i gave some wrong host key and also hostkey as empty.
I found even with wrong host key and empty hostkey , my scripts working fine..i can able to SFTP the files too.

Is that mean host key is not required for connection ?

can anyone help me?

It is not required, if you have the correct host key fingerprint cached in registry already.