double line at the bottom of a table row

If this is not the border of the table it could be the bottom border of that individual cell.

To inspect the bottom border of that cell do the following:

1. Select the cell; you can do this if you select text in the cell and hit the "Esc" key.

2. Then inspect the Control panel's widget for cell strokes.

3. Select the bottom cell stroke only.

To do that click the left, the top and the right stroke of the cell widget so that only the bottom one is showing up in blue.

Screenshot from my German InDesign showing a selected cell and the Control panel.

Look closely into the widget with the cell strokes. The blue one at the bottom is the active one.

All the gray ones are not active:

Then inspect the values for stroke weight, line type and color.

Set stroke weight to 0 and stroke color to "None":

FWIW: You find the Control panel under menu Window.

Regards,
Uwe Laubender

( ACP )