Yeah, I get slightly lower numbers for TWF, I'm guessing because of the crit calculation. I also get slightly higher numbers for BB starting at Level 9; I'm not sure what that's about. The bottom line still holds that TWF yields slightly higher DPR at all levels if you ignore the possibility of BB's secondary damage, significantly so in Tier 1, but by the time BB starts to scale, the gap is pretty small as a share of the average damage; small enough that IMO the combination of the control effect and being able to do something else with your bonus action is well worth it.
Example
TWF (level 5)
Main Hand (base damage): (1d6 + 4) * 0.6 = 4.5
Main Hand (crit damage) : 1d6 * 0.05 = 0.175
Off Hand (base damage) : 1d6 * 0.6 = 2.1
Off Hand (crit damage) : 1d5 * 0.05 = 0.175
Sneak Attack (base) : 3d6 * (1 - 0.4*0.4) = 8.82
Sneak Attack (crit) : 3d6 * (0.05 + 0.4 * 0.05) = 0.735
Total: = 16.51