Merge only differences in the rows in a power query

Thank you, Ahmedx. I am trying to implement the formula/steps with the real complex file. Could you advise at what step did you create and insert the trans formula ? I am entering it within the table , but When creating it - I got and error:

An error occurred in the ‘Table’ query. Expression.Error: We cannot convert a value of type Function to type Table.
Details:
Value=[Function]
Type=[Type]

Ahmedx  Hi, I mentioned that the formula merges only the first two rows. But sometimes we have 3-4-5 rows with the same TagID. Can I emend the formula adding column3, 4 etc? or somehow to calculate the number of the required columns first and to merge them based on this? Irevised the example excel file adding third row with TagID 12 for example

= (x)=> [
t1 = Table.Transpose(Table.DemoteHeaders(x)),
t2 = Table.AddColumn(t1, "Custom", each if [Column1] = "Element:Text" then [Column2] else if [Column2]=[Column3] then [Column2] else Text.From( [Column2]) & " /// " & Text.From( [Column3]))[[Column1],[Custom]],
Results =Table.PromoteHeaders( Table.Transpose(t2), [PromoteAllScalars=true])][Results]