When I reclassed 31B, there were former 11Bs that were in my class and had it sewn on their BDUs. Based on that group of badge, you cannot then earn a CAB and wear them both at the same time.http://en.wikipedia.org/wiki/B...e_United_States_Army
As described in Army Regulations 670-1 Uniforms and Insignia, badges are categorized into marksmanship, combat and special skill, identification, and foreign. Combat and Special Skill badges are further divided into five groups.
Soldiers are authorized to wear a total of five badges from the marksmanship and combat and special skill categories; no more than three can come from the marksmanship category, only one badge each from Groups 1, 2, and 3, three from Group 4, and two from Group 5. And only two identification badges are authorized over each pocket.
These badges are worn in order of precedence (Group 1 the highest). Marksmanship badges are worn after any special skill badge. Badges within the same group may be worn in any order.