Middlesbrough have been approached by fellow Championship clubs who harbour suspicions that their pre-match training sessions may also have been spied on by Southampton. The English Football League has charged the south-coast club with misconduct after a member of Tonda Eckert’s backroom was allegedly caught breaching regulations by filming and making audio recordings of one of Kim Hellberg’s final practice sessions before his Middlesbrough side faced Eckert’s Southampton in Saturday’s playoff semi-final first leg at the Riverside Stadium. As Hellberg prepares his players for Tuesday’s second leg at St Mary’s Stadium with the score goalless, Championship rivals are understood to be examining any available CCTV training-ground footage from recent weeks. Images of the alleged spy, believed to be a Southampton first-team analyst, being apprehended by Boro staff at the team’s Rockliffe Park training base near Darlington on Thursday have been widely circulated.…