Selling the bar rather than the ores yields an extra 13 per bar. Selling the bar rather than the ore yields an extra 4 per bar.
The bars also sell for significantly more than anything that can be made from them. Once a complete set of Crimson equipment has been made, it is more profitable to sell raw bars and tissue samples.
In 1.4, the value of Crimtane Bars was decreased and the value of Crimtane Ores was increased, such that three ores sell for exactly as much as one bar. Hence, it is more efficient to just sell extraneous ores.