Short answer:
gPhotoShow Pro with default settings doesn't repeat pictures until all pictures have been displayed. You probably have very similar images in your configured folders.
Make sure that the option "Save files list between sessions" in "File options" page is ticked (default setting), and no folder is listed more than once in gPhotoShow images list.
If you are not using filters and global weight images will not be repeated.
Long answer:
gPhotoShow Pro removes displayed images from its internal list and periodically this list is saved to disk, for this reason it can't repeat images, however there are some settings that may cause slideshow to restart and then repeat some images while others are not displayed.
If you are using filters with multiple monitors it is possible that the slideshow is restarted quite often and this could cause some pictures to be repeated.
If you are using global weights and the option "Repeat images with weight greater than 1" in "File options" page then images with weight more than 1 will be repeated.
In any case to check if images are repeated or duplicated you can enable filename display in Information page or enable the option "Create displayed image list" in "File options". This last option allows you to check displayed images from more than one session and to see when slideshow is restarted.
Unfortunately there is no way for applications to have the same numbering used by windows, the official Microsoft answer is "It was never a design goal to provide a way for applications to label monitors with the same IDs that the screen resolution control panel uses". Starting from v7.4.4 gPhotoShow Pro displays position and size of the selected monitor this should help to identify it.
The issue is caused by the security constraints enforced by Windows 10, the screen saver runs on his own desktop and user desktop is hidden before the screen saver starts. There is no way to fix or to workaround this behaviour since it is a basic security feature of windows.
The issue is caused by the security constraints enforced by Windows 10 (and 8.1), a screen saver has no way to interact with user desktop so for some operations gPhotoShow needs the ControlSS utility running on the user desktop. One of these operations is setting the last image as wallpaper. If you don't wish ControlSS you must disable the option to set the wallpaper. Unfortunately there is no other solution.
Screen saver settings can be exported/imported very easily by running the Slideshow Maker program.
- To export (save to file). Run gPhotoShow by using the shortcut "gPhotoShow SlideShow Maker", click on the Load button, from the menu choose "Load from Registry" then click on the button Save, choose "Save to file as..." and save to a file of your choice.
- To import (load from file) . Run gPhotoShow by using the shortcut "gPhotoShow SlideShow Maker", click on the Load button and choose "Load from file", browse for the file you previously saved and click on Open. Now click on the Save button and choose "Save to Registry"
The error log and files list caches are usually saved inside the user profile directory: c:\users\your-user-name\AppData\Roaming\gPhotoShow
However if gPhotoShow runs as logon screen saver that location is usually not available so gPhotoShow saves them in the windows temp folder: c:\windows\temp\gPhotoShow
Starting from v2.5.0 gPhotoShow installs a custom version of ControlSS, this ControlSS version can change the gPhotoShow Screen Saver configuration either automatically or manually. The first thing to do is to create a .gss file for each of your category and put them in a folder. Then, after you have installed v2.5.0 or later, you must configure ControlSS to use that folder. To do this open the ControlSS menu and select "gPhotoShow Settings" -> "Configure", in the window that opens set the folder where you stored the gss files and set the automatic change options (if you like them). After you close the window all the gss files you created are listed under the "gPhotoShow Settings" menu and you can now easily change category either manually or automatically.
Removing that context menu item is very easy, from the windows start menu run "gPhotoShow SlideShow Maker" then click on the button "Tools" and from the menu choose: "Folders Context Menu" -> "Remove item Start Slideshow with gPhotoShow"
Open Windows Explorer, find the directory where gPhotoShow is installed (usually c:\program files\gPhotoShow) right click on the file gPhotoShow.gss and choose "Edit Slideshow".
Open Windows explorer, find the folder where you stored your pictures, click with the right mouse button on the folder and choose "Start SlideShow with gPhotoShow" from the context menu