ONLY ONE SONOGRAM DURIN PREGNANCY.. IS THAT RIGHT EVEN IF I REQUEST FOR A SENCOND ONE?

With my first pregnancy i was so excited, lk most usually are..at 18wks i had my first sonogram & was even more thrilled to find out what the of the baby was..i ended up leave the office still not knowin cz my plasenta was in the way..:( i request for another sono so that i could prepare myself for the new bby with clothes & so on..my dr said that the bby&i were healthy so he wasnt gonin to do another one..so it ended up bein a suprise when i had my son in 2008..now that im pregnant with my 2nd..im scheduled for my first sono at 20wk nxt wed..i wanna knw so bad what im goin to have, but have fear that it might be a suprise all over again..& yes its still the same dr..i live in a small town & no other dr was accepting new patients..so i was stuck again w/ Dr.R ..but when he delivered my son it went well..but again if i dnt find out what im havin nxt wk..should i fight to get another sono or will i just make myself look stupid & selfish for wanting to find out the of my unborn bby??