Problem uploading images with FCKeditor Resources Browser

Recently came across following problem - when I try to upload images with "FCKeditor - Resources Browser" in Opera, i get this JavaScript warning - "A file with the same name is already available. The uploaded file has been renamed to "...(1).jpg". If I press "OK" the warning appears again with higher number in the file name. It won't stop unless I check "Stop executing script..." box. Afterwards, there are several (at least 2) identical images uploaded.
This happens only in Opera. Firefox and Chrome work fine. The problem appeared only recently, I guess, with release of last Opera version.
I know, obvious solution would be to use another browser, but some of my clients still prefer Opera (don't know why).
So, if anybody can help me, I'd really appreciate it.
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MODx Evo 1.0.5
Opera 11.52

Hello,

I see this post is 1 year old but I have same problem and didnd't find other post on the forum for this.

I use Opera 12.02 on MAC OS X with MODx EVO 1.0.8.

I get same message and same behaviour : image is created twice.

Thank you for any idea