Shown in the tool tip of these two items. Irestone of Sharp Sight is apart of the Knowledge of the Past ability line. Shawl of Eternal Focus is apart of the Soothing Breath ability line. Instead of the click on these items going to the item effect line listed they are instead going to the same line and overwriting each other.
What Yep said above but to be more specific, Aura of Eternity is part of the line that is later known as Soothing Breath, and MMM is part of the line that is later known as Knowledge of the Past. As he said those 2 lines have stacking conflicts so you are only allowed to choose one of the lines, Soothing Breath line overwrite Knowledge and Knowledge overwrite Soothing Breath thus the meaning of the focus description. It was confusing design when every iteration was a uniquely named focus in the line, trying to determine what you are missing and what you need to get to upgrade.
I don;t see how it is bugged. Maelin's is knowledge of the past so overwrites soothing breath (note it has more mana regen than hp regen), and aura of eternity is soothing line so overwrites knowledge (note hp and mana regen is the same on it). KoTP is more mana regen Soothing line is the same hp/mana So not sure why you think anything is incorrect?
I'm also not seeing the bug based on your screenshots. In the first screenshot, you have "Item: Aura of Eternity 2/31." In the second screenshot, you have "Item: Maelin's Methodical Mind 3/32" and no longer have Aura of Eternity. So one of them overwrote the other and went to a different line. The only confusing thing is that the Knowledge of the Past and Soothing Breath lines had other names at low ranks. At some rank soon, the item effects will just be Knowledge of the Past and Soothing Breath followed by a roman numeral.
The super confusing part is, that each time you overwrite one of the lines, the spellgem-bar layout reverts back to a 2-line layout.
I would remove one of the effects from the game or make them more different. 2 x mana or hp depending on the effect.