I'm not clear on what's happening. Are you unable to update an existing resource, or are you having trouble creating a new one with the same pagetitle as an existing one?
If it's the second one, I suspect that it's the alias, not the pagetitle that's causing the problem. Check the allow_duplicate_aliases System Setting.
discuss.answer
&aliastitle=`0` did it due to duplicate alias title - thank you Bob.
[ed. note: sspind last edited this post 9 years, 8 months ago.]
I'm glad you got it sorted. Thanks for reporting back.