SQL product many categorys

Using SQL server 2012 and office 365 excel; I have the following example data in a table:

Columns: pd_code, height,width,length, pd_catdesc, Category

Data example: derp,1,1,1,derp desc, cattop>>catmain>>catsub___18

the total rows when i select from my table is 10976, if i take out category and group by all other columns i get 10691 (correct unique parts).

Reason

A product can have more than 1 category. The issue I face is for an import. A product has a category defined like...

category___18;

If I want to add multi i need to simply add a semi colon

category___18; category___20;

From the data as you can see my category field is actually the tree, i have some excel code that rids me of all but the sub category. Excel code

=TRIM(RIGHT(SUBSTITUTE(CR3,">>",REPT(" ",250)),250))

category___18;

What I need

what I need to do to the data is to filter out those multi catgeory products. so I can do a bulk import of single category products.

then I need to do a new query that somehow will take all the sub categorys for a product and create a string like

category___18;category___20;

Summary

So I need to only return unique rows based on pd_code but contain a column that will display a subcategory like

cat___18;
And any other categorys like

cat___18;cat___19;