This is for a pen plotter that I use sometimes to watercolor. I need it to go to the water color dish after every circle. Normally, I just manually paste in place a small circle where the water dish is after every few objects, but I want to automate it. I know I can do a version of this with Vpype, but I am wondering if there is a way to do it in Inkscape? Essentially paste the exact same object in the exact same place (not relative, although relative position could work because I can fix afterwards) every other or every two objects.

Is there a way? thanks!

Honestly I´d try to go with a water tank brush filled with watercolour (like Sakura Koi Water Brush) instead.

Unfortunately that doesn't really work—I wish it did! The water requires pressure to come out. Those pens are great for hands, not so much the machine. Sending a brush to a water bowl works well and usually you can program it in when programming the SVG, but in this case I need to add it after and manually is a bit tedious. 

If there is no Inkscape option, I think I'll just use vpype to do it.

I have some from Kuretake.Ltd and absolut no pressure is needed, maybe the pigments stuck in the fibres - I guess a tiny hole at the end of the shaft could prevent the brush from getting any under pressure when releasing the watercolour. You could also try acrylic inks (the ones used for air brushing or dyes which contains no pigment at all.)

If all the shapes are in the same layer, get all shapes in a list, then make a list of ids for every n object (before modification) and use  .duplicate on the water then .addnext() or .addprevious() for the n object list.

@Polygon interesting, I have a lot of water brush pens—I use them with my hands—but I can't get any off them to continuously flow water without manual intervention using the pen plotter. I use them with water only, no ink. They simply don't give enough water onto the page. But I'll look for the brand you mention and see if it would work because that would be awesome.