This is a stacking indicator. It means you have two photos stacked on top of one another. You can view the stacked photos by Photo->Stacking->Expand, or by double-clicking on the vertical bars that appear near the bottom of the photo frame (for example, just to the left or right of "Soren Chr. Madsen?". You can also unstack, or change the order within the stack. How to stack photos in Lightroom
Lightroom makes suggestions as you type a name so you can quickly press entre/return or click the checkmark. Initially this helps with the indexing so face recognition should become more reliable over time. You can also drag and drop from Un-named to a stack in Named. The people tag is a special keyword which is also region specific which may affect detection e.g. in a group photo.
You can set Lightroom to index an entire catlog (caution with large catalogs) or choose to do it one folder at a time which can sometimes help speed up the initial indexing depending how you organize your LR Library.
This link has further information which may help.