I recently started having problems with breakpoints in Visual Studio 2010. When I set a breakpoint and then start debugging, another breakpoint appears on some other line nearby. The screenshots below shows the editor after I set a breakpoint, as well as the breakpoints window:
As soon as I start debugging, the breakpoint duplicates, as seen in the following screenshots:
Why is this happening and how can I stop it?
It looks like there is a child breakpoint set up, as described in the following MSDN articles:
http://msdn.microsoft.com/en-us/library/b98cwcyw.aspx (Link dead, see
Child breakpoints VS 2010)
http://msdn.microsoft.com/en-us/library/02ckd1z7%28VS.71%29.aspx#vctskbreakpointswindowchildbreakpoints
Here is a similar question on StackOverflow, for which one of the answers contains a macro to remove child breakpoints. Perhaps that might work for you? Disable/remove child Breakpoints?
Alternatively, deleting the parent breakpoint (which will also remove the children) and re-creating it might help to resolve the problem.
I suspect it is because of mismatched newline endings. I had similar issue - multiple lines were marked as breakpoint location (say, 10 lines). Later I found it was because of only \n or \r present, instead of CRLF sequence.
Use Save-As, select Save With Encoding.. option under Save button in SaveAs dialog box.
I had the same problem in VS 2008 and I resolved by getting rid of the duplicated .dll files in the compiling / debugging folders.
Please refer to my full response here: https://stackoverflow.com/a/50063517/3603386
Do you use F10 (step over) when debugging?
F9 is the shortcut to add/remove a breakpoint, you may be inadvertently hitting that.
来源：https://stackoverflow.com/questions/9130749/why-do-my-breakpoints-duplicate-in-visual-studio