Expanded data incorrect when merging two queries

Hi All,

I've got a problem where I've merged queries, and yet somehow when I expand the data the data that is output comes from a different query... not the one I originally merged to! 

The source query has a column (Design Package) which it shares with both the query I merge with and the query that the data ends up coming from. 

My coding at the merge queries step looks like this, where the table being merged with is "BaselineStartDate":

let
Source = Table.Combine({DataConversionCostA, DataConversionCostB}),
#"Merged Queries" = Table.NestedJoin(Source,{"Design Package Name"},BaselineStartDate,{"Design Package Name"},"BaselineStartDate",JoinKind.LeftOuter),
#"Expanded BaselineStartDate" = Table.ExpandTableColumn(#"Merged Queries", "BaselineStartDate", {"Earliest Date"}, {"BaselineStartDate.Earliest Date"})

in

#"Expanded BaselineStartDate"

However, the data that results from expanding comes from a separate query called "UpdatedStartDate".

I know this because I've cross-checked the date which is expanded with both queries and always the value represents that from the "UpdatedStartDate" query, not the one I merged with: "BaselineStartDate".

Does anyone have any idea why this would be?

Seems like a basic merging step so not sure how it could be wrong.

Thanks for your help!