(of a house) Having a party wall at the rear

Example:   Ruth and Gehrig hit back-to-back home runs.
  They sat through two back-to-back movies.
2011 February 12, Les Roopanarine, “Birmingham 1 - 0 Stoke”[1], BBC:
  An injury-time goal from Nikola Zigic against an obdurate Stoke side gave Birmingham back-to back Premier League wins for the first time in 14 months.
With one's back facing that of somebody else.
  We lived in a row of back-to-back houses.