The Phillies attendance figures for the streak are noted below - 2003 is a partial season only reflecting games after May 15th when the Red Sox streak commenced.
So it turns out that the Phillies drew 31.7 MM fans during the sellout streak, while the Red Sox drew 29MM. The difference was 2.7MM fans. Which is actually more then the entire 2005 draw for the Phils.
Of course as anyone who attended a midweek "sold out" Phillies game in 2012 can attest the Phillies were likely beefing up their own numbers during this time period as well. Thus the title of the post re: Imaginary Fans.
As always MLB attendance figures are for tix sold (which likely includes tix given away/written off) and do not reflect turnstile attendance.