You will run into a lot of issues here because of blending. When you blend data all the data from one side of the blend and all the data from the other side of the blend are related based on the field you've chosen as a relationship. When showing dimensions in the blend afterwards (putting blue things on the rows shelf) we are only able to match identical fields on both sides. So if the primary blend has inside of the blended field an alias (let's call it) Alpha and that same Alpha is related to Alpha on the secondary data source but then there are two different field in the secondary you're unable to see them both. Because you cannot aggregate two different dimensions and anything from a secondary data source must be aggregated.
Blending Field Extra Field
When you put Alpha on the rows shelf from each everything will match but if you put extra field on you will get
Alpha Alpha *
Beta Beta Squirrel
The way around this will be to find a truly unique identifier. If things in the one of the data sources are not truly unique for each site id or site name then you will continue to have trouble. Alternatively you could bring these the same excel workbook which would allow for the controlled usage of joins or custom sql.
thanks a lot for the answer. So at the end without Raw Data manipulation I do not have a chance to get this sorted. Ok I will make some thoughts how I can get this Site ID Unique.
Thanks a lot for your help