Season 10, leg 1 was a mid-leg elimination, not a double-elimination at the same point.
One reason why I'm skeptical of a double elimination is that historically, the show doesn't do as well in the ratings with too many NELs (or their equivalent.) This season is likely to start on September 18th (the previous Sunday being the 10th anniversary of 9/11), and 12 straight episodes would take it to December 4th. A double elimination would make it harder to cover that schedule without four (or five) NELs or equivalents....and even if the premiere was the following Sunday (the 25th) a 12-episode order would only take it to December 11th. Given how CBS wants to air Survivor season finales on Sundays (given them December 11th, more likely, as December 18th would normally be a Hallmark holiday presentation) I just don't see the show wanting any more NELs than they need to.
Edited to clarify which dates are September and which are December, as the same days of the month fall on Sundays!