Is there an way to import or export pictures in Lightroom Classic with a sequence of 2.
e.g File_1; File_3, File_5 and so on.
Or do i have to write an external script to solve this issue?
You'll have to write that script.
You can do this as an Export, but it requires extra steps. Select all of the files, right-click, and select Create Virtual Copies. Use the Filter Bar> Attribute to select just the virtual copies, and add a keyword such as Virtual. Export the files and choose the sequence renaming of your choice. Go to the Export folder location and use the Filter bar on the keyword you assigned above. Delete these even number file copies.
Just out of curiosity why do you need this sequence numbering? Perhaps we can come up with a better solution if we know what you're trying to do.
I'm using my camera to digitize my grandmothers photo albums.
I build a camera holder for this. So I'm first taking pictures of the odd sites. Then turn around the photo album an taking the even sites.
Another option for 'Import':
Rename the files (in a hard-drive folder) BEFORE importing. Then use the [Add] option in the Import.
A File renamer like Lupas Rename can easily insert a sequence number incremented by 2.
Edit: Silly me! included an .XMP file in the rename screen-clip. This would be a mistake!!
For 'Export' -you could export with a sequence 001,002,003,004,etc, then use Lupas Rename to 'Remove the Lr sequence numbers (the first 3 chaaracters) and insrt the alternate sequence 002,004,006,etc.
If you have ALREADY imported the files and edited them in LrC you can do this using the technique I outlined in this thread. The person was doing a book like you.