Reason for repeat lines in User Macros?

[Rongway]

As long as you are not rapid firing your buttons things should go off just fine. If you are the type that click click click click clicks tho, then you may cancel the macro before it goes off, which can happen by even pressing a different skill. The only other reason that things get skipped in macros usually is by having multiple skills with no wait times in between.

Pressing the button a second time while it is already running will restart it from the top, yes. This can be disabled by using an /mlock at the beginning of the macro.

/mlock
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/ac (Some Action) <sometarget>
/micon (Some Action)

Non-macroed actions do not interrupt the currently running macro regardless of lock status, and can be used freely without disrupting, i.e., a long macro wait.