On a split button, if the main button has the same behavior than the caret button (open a dropdown menu for example), then it should be a regular dropdown button and not a split button.

An example of such behavior is visible in current document plugin when user does not have all permissions on an item for example (see attachment).

However the behavior is different (for exemple main button is [update] which opens a modal and caret button which opens the menu) then we should keep the split button.