Duplicating post with featured image name in cyrillic doesn't work properly

[ge-ku]

Steps to reproduce:

1. Rename any image into something that contains cyrillic only, like "гп.jpg".
2. Upload it to one site and publish a post with this image set as featured.
3. Duplicate post using this plugin.

It refers to this image simply as ".jpg" and when you publish multiple posts like this it will use same picture everywhere (I guess the first instance of ".jpg", not sure).

Possible solutions:

1. Support unicode file names.
2. Transliterate file names into latin.
3. Use new filenames unique for MPD plugin (like multisite-post-duplicator_i.jpg where "i" is incremented integer).

Thanks for your work on this plugin, hope you can fix it. Let me know if this issue is on my side only.

[ge-ku]

When I echo $filename after $filename = apply_filters('mpd_featured_image_filename', basename($image_details['url']), $image_details); in mpd-functions.php I get .jpg.
$image_details['url'] is /wp-content/uploads/2017/09/\xd0\xb3\xd0\xbf.jpg.

I thought that maybe those backslashes are what causing storing images without filenames. Doing $filename = basename(str_replace('\x', '', $image_details['url'])); however did nothing.

Also, thumbnails work correctly, since they have unique-ish names with appended resoultions at the end.

[ge-ku]

As a temporary fix this worked for me:
$filename = $image_details['id'] . $filename;
It just prepends id to filename, making those empty ".jpg" into something like "14143.jpg". This is not a proper fix as it doesn't preserve original filenames but is good enough for me, still hope you can fix it for real :)