How many Presidents Do we have in the USA at one time?

okok...it's after 4am..and I am sick of this damn commercial where Clinton and Bush Senior and raising money for the tsunami victims, a worthy cause but heres my gripe.. They say they are asking not as Presidents but as private citizens....Hello0o0o0o00ooooo....ummm..thats what they are after their term in office..they are Mr Bush and Mr Clinton. Somewhere people stopped saying ex-President and started refering to these people as President long after they are in office. I believe we only have one asshole atta time in the Whitehouse~!!