Careful comparison of the photos of Jeremy Corbyn at the wreath-laying ceremony in Tunis in 2014 has been made by "London DADA" on Twitter, which I reproduce above. He is a Corbyn supporter and he is not convinced by the Daily Mail story, so there is no anti-Corbyn bias in this presentation. He confirms the position in which Corbyn was standing during the ceremony and raises the relevant question, 'Was the plaque where Corbyn laid the wreath the one shown in the Mail article with an inscription honouring the Black September "martyrs" (below)?'
The plaque with the inscription in Image 2 appears to slope from a tomb near ground level towards the ground. In the background of the centre photo in the collage at the top of this post (Image 1) is a number of plinths at waist-height with inscriptions, and one nearer the front of the photo, indicated at 3, which appears to correspond with the plaque in Image 2. Corbyn appears to be standing by a plaque at knee height, which also corresponds with Image 2.