Is it normal to have bm twice a day?

Can be. Bms typically vary from person to person and can be normal but differ completely and still be normal. There are people who go once every three days and that is normal for them. More of a concern would be a change in bowel habits. Also if bms are associated with abdominal or rectal pain, blood associated with them all are concerns and should be evaluated by a physiaicn. But bms 2x a day can be nl.