Darren, I'm building my specs per the pressure classes laid out in SMACNA, so they're going to be different for rectangular and round. You answered my question though. I've got my specs and rec & round templates built, it's just a question of copying & pasting.
If I'm understanding you correctly, you're building separate service template for rect/round?
I get SMACNA has different specs for rect and round. But a single specification can contain both, rect and round specs.
Create a new spec. One of the dropdowns below the name shows the "Shape". This is NOT assigning a shape to the spec.
Set the drop down to RECT. Add a few entries. Now set it to ROUND. The bottom of the screen will change columns. Add a few entries. Now change it back to RECT and you'll see your original RECT entries.
This is similar to the STRAIGHT/FITTING/BOTH dropdown as well as material.
However, in the case of material, while you CAN have different entries for different materials in the SAME spec database entry, it's best practice to build a SPEC per material.