I think the answer is logical - if the compiler is the same, then the output files are also the same, so the security is the same. Well, I think that technically every time you compile a file, the contents of the output file are not exactly the same, maybe there is something that changes every time. Or at least this was before. By "same" I mean that they are produced by the same program - metaeditor.exe.
By the way, still there can be difference between the files generated on the server and locally. Because there are few options when you compile them. Normally you can get .mq4 file from somewhere, open it in MetaEditor and hit Compile. But it is possible to create a project in MetaEditor, which contains one extra .mqproj file and then the project has this:
0_1561382667009_29abe87c-9ddb-42cf-aa9b-7a66aa893dbd-image.png
As you can see, there are some checkboxes and they for sure change the contents of the output file. Also the speed of compilation. And sometimes the ability for the EA to produce bugs... I noticed few times that the EA behaves differently when the additional optimization is turned on or off. Maybe these are the default settings for every .mq4 file without .mqproj. I think on the server some of these options is turned of.