yes mam you sure can when i was preg before i found out i had light brownish redish discharge..
its the implantation of the egg
you might or might not expereince cramping
I agree with ems19 you can be once again I would talk with your doctor and get some blood work done asap.
There is definitely a posibility that you are pregnant again, you are more fertile after having a baby but it could be that your periods haven't returned to normal after your baby yet. I would leave it a week and do another test to be sure.
Hope this helps.