When trying to create a folder with the same name as one that has already been created. The snackbar message states "Method not allowed".
I think the message should be a bit more informative like "Folder with same name exists" of another forlder should be created with suffix "
Can this problem be reproduced with the official owncloud server?
(url: https://demo.owncloud.org, user: test, password: test)
Yes.

@davigonz @jesmrec I think this is an issue and if you agree with this then I would like to make the change its just a minor one.
go ahead
@jesmrec Which one of the following should it be? The message should be a bit more informative like "Folder with same name exists"? or another folder should be created with suffix " + 1".?
we should follow the same behaviour the web UI. In this case, it i not allowed to create a folder with the same name as another existing one. Web UI displays the message <folder name> already exists
What error does the server send in the HTTP response? Could you post it here?
The response of the MKCOL request is a 405 error with:
<s:message>The resource you tried to create already exists</s:message>
The error shown (method not allowed) corresponds with the RFC standard for such error code
https://tools.ietf.org/html/rfc2518 , section 7.4