HTTP 413,417 instead of 400?

Hi all,

I am trying to testing my server ability with the mod_security.
While testing, I found double Content-Length will give me http 413
instead of http 400, which I found in both access log and audit log;
but the browser give me http 413
(This appear in another server as well)

Also, same condition appear in Expect attack, 417 received instead of
400, which I trying to insert javascript code in the Expect header
field.

Can anybody give me explanation? I am using the default rule set with
default setting only.

Thank you,
Vic

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