This is an expected behavior. Though this workflow might have been possible in Embedded Coder R2014a, it was not an intended or desired workflow. Hence, it is no longer supported in Embedded Coder R2014b and later releases.
In Embedded Coder R2014b and later, if you have different signal objects connected to different signals, you need to use different get and set functions for these. Alternatively, you should use the same signal line for common get or set functions.
Though not recommended for code generation, you can use the following workaround to avoid this error during simulation when multiple signal objects share get or set functions:
(1) Open the 'Configuration Parameters' editor for the model.
(2) In the 'Code Generation' pane, select the ERT-based 'System target file' (ert.tlc).
(3) Enable the option 'Ignore Custom Storage Classes'.
