You asked for a letter matching 1112 even though your actual work experience didn't match it? That is a misrepresentation and is a serious offense. Do not do such a thing again.
Both 0013 and 1111 are eligible NOCs this year. Both of them are filling up much more slowly than 1112. If you can get an HONEST letter showing at least 1 year of continuous full-time experiencein either NOC, I suggest doing so and applying under one of those NOCs.
The problem is that it is possible that CIC has a record of your former application, since they opened it and evaluated it to determine whether you made the pass mark. Nobody really knows whether they keep full records of all applications even those rejected at an early stage. But if they do, it's going to look very bad that your employer's letter last year stated duties for 1112 and now states duties for a different NOC.
If you have a different employer that can give you an HONEST letter for an eligible NOC that doesn't contradict a letter you sent with your previous application I suggest going with the different employer. If you have no choice but to send a contradictory letter, you'll just have to take your chances.