Made a recording with ObjectCount event enabled, with period Once Per Chunk
When opening this, and viewing the Memory table, I can see two rows for quite a few object classes, like char, java.lang.String, com.perforce.p4java.impl.generic.core.file.FileSpec etc.
The lines have different values in the other columns.
My guess is that the differing lines come from different chunks.
Once the page is redrawn, by navigating from and back to it, or doing an explicit reset of the page, this behavior disappears, and the data for the classes are merged together in the same row.