Why is that so important to know that? Because the pellet cave (the age with 2 linking levels) is linkable only by same level combo of "Ahnonay Cathedral - Er'cana".
You cannot link to same pellet cave not being in the same level above mentionned ages.
Now the bug is why those 2 instances of each age (the ones you deleted and the new ones appear at same time in your "Personal Links")...
The way it has always been on MOUL that I've seen is:
1 - Er'cana
2 - Ercana
3 - (1)Ercana
X - (X-2)Ercana
Never giving you the apostrophe one except for the very fist time (same for Ahnonay Cathedral and the space), and not even then if you first make the age by sharing the book. However, I never tested it here on TOC, so I don't know if it is slightly different here or not.
It's pretty weird he has two of each age at once, and that he has his own copy of the Great Zero.