This is volume 2 of Le Journal de Mickey, the french Mickey Mouse comic.
Vol. 1 ran for 390 issues, vol. 2 recently published its 3000th issue. (dec 2009)
Due to a strike, #1256 was delayed for two weeks and instead during those weeks, a second and third #1255 was released (all with different covers/content).
Some issues are double issues.
70 double issues, 21 issues with the same issue number.