"although Pro say the PLT has a recessed groove for cable routing it's nothing but the smallest of creases in the crook of the bend above the lever, more of a subtle guide for the cable rather than a bona-fide recess which might lead to unsightly bumps and grip-comfort issues, especially if you need to run double cables under the tape."
*Single recessed groove cable routing.
"although Pro say the PLT has a recessed groove for cable routing it's nothing but the smallest of creases in the crook of the bend above the lever, more of a subtle guide for the cable rather than a bona-fide recess which might lead to unsightly bumps and grip-comfort issues, especially if you need to run double cables under the tape."
http://road.cc/content/review/26135-pro-plt-compact-drop-bars
these easton ones have double groove, inside and outside, i have them on one of my bikes, but the ergo shape is not that great for my hands
https://www.cyclingdeal.com.au/buy/easton-ea70-ergo-road-bicycle-drop-handlebar-31.8/OT-HB-EA7