Expanding column after left join shuffles values in single column

Hi all, 

I cant figure out what is going on in the case below. Hope somebody can tell me what I might be doing wrong. 

So I merged two tables based on the columns "UOKey" and "RepetitionNr". So far so good, when I check the individual rows, the join was succesfully performed, just as an example, see that row 1 matches up nicely (UOKey and RepNr). All other rows do too. 

Now when I try to expand the rows, something strange happens. The columns in the row "EVENT_TIME", seem to shuffle for now clear reason. I assume that since I am only expanding, all rows of my UnitOperationStart (The starting table for the join), should remain tied together. But when I expand, see that the event times seem to shuffle, e.g. RepetitionNr 1, for UOKey "EMZ239D1BBRE521625LEGEN" first had event time 06:03:51, after expanding, it has 14:16:31 (see below) .

I would not expect this to happen. Why doesnt row 1 (or any row with repetition nr 1 and uokey "EMZ239D1BBRE521625LEGEN" still have EVENT_TIME 06:03 and the merged EVENT_TIME.1 of 06:39.38)? 

Please help me, this is driving me bonkers! Thanks in advance

Here is my code from the advanced editor 

let
    Source = UnitOperationStart,
    #"Removed Columns" = Table.RemoveColumns(Source,{"BatchID", "Unit", "UnitOperation", "Label"}),
    #"Merged Queries" = Table.NestedJoin(#"Removed Columns", {"UOKey", "RepetitionNr"}, UnitOperationEnd, {"UOKey", "RepetitionNr"}, "UnitOperationEnd", JoinKind.LeftOuter),
    #"Changed Type" = Table.TransformColumnTypes(#"Merged Queries",{{"EVENT_TIME", type datetime}}),
    #"Expanded UnitOperationEnd" = Table.ExpandTableColumn(#"Changed Type", "UnitOperationEnd", {"EVENT_TIME", "RepetitionNr"}, {"EVENT_TIME.1", "RepetitionNr.1"})
in
    #"Expanded UnitOperationEnd"