I just did a simple test because what you said didn't sound right. I can use UpdateListItems in Custom List and add as many items with an identical Title value as I want. There's no uniqueness required.
Perhaps you've set something to require the uniqueness? In 2010, there is a setting for this on the column settings page: "Enforce unique values:".
M.
Perhaps you've set something to require the uniqueness? In 2010, there is a setting for this on the column settings page: "Enforce unique values:".
M.