小明(A)同大明(B)
A, without the consent of B, lets the firm to sell licensed drugs. If this is a limited company, the power should be in the hands of the Board of Directors and not necessary they are the shareholders. The question is telling A and B are owners. They are then operated in the mode of a partnership firm. They are joint and severally liable for all the liabilities incurred by the firm. B is still liable for the illegally act of A on behalf of the partnership firm.
A limited partnership is still a partnership and is not a legal person and hence each of the partners is jointly liable except there is a limit on a particular partner. It is therefore a partnership in which only one partner is required to be a general partner having full liability.