Flickr and aperture sync - date and time out of control

I do quite frequently sync to Flickr by the Aperture built-in plugin. As I rely on a proper time stamp of my photos in Aperture I do keep track of those. But in the case of the synced pictures this is totally out of control:

A picture might be taken on date 1(taken) and imported to Aperture on date 2(import) and shared to Flickr on date 3(shared). What I would expect now looking at Flickr online is that the date stated for taking the photo would be date 1(taken)... instead it is date 2(imported). So I changed the dates manually in the past online in Flickr, as in the EXIF view all dates are reported correctly (Some might wonder why that is, as Flickr should interpret the given date there). A few days later after Aperture has conducted its sporadical sync a picture shared would be a total mess: I do get an additional date, lets call it date 4(random resync) for taking the picture, which cannot be related to any of the previously mentioned dates 1-3. Funny enough, this does not always happen consistently. Some picture do stay in accurate sync, but just a small minority.

Is this known? Is there a fix? I haven't figured the whole thing out yet, but it does not seem right. All systems fully updated, AP3, Canon 5/1/300D, just in case the EXIF protocol matters.

Regards