Installing double-pole line voltage thermostat for 2 baseboard heaters
Two long for a Comment: It looks right after a couple more sips of coffee.
I did not follow your wiring , not enough coffee yet. But I think your old thermostat is only breaking 1 side for each heater, this is a trick we used to do to double the ability of a single thermostat. We would tie the whites together with one of the hots (usually the white hot and Mark them black) we would then use the supply or other hot to both of the line sides of the stat. Next we would put 1 heater on t1 and 1 heater on t2 this way a double pole stat could control 2x it’s listed ampacity (but each would be be below the max) this worked great since most rooms have multiple heaters. Yours are both in parallel on one contact I would have split them up so the stat would last longer. As you did and yes it looks like you did it correctly. Please verify your new stat is listed for use without a neutral. Some can use the ground and some require the neutral, and some only need the 240v but it looks good.