ok thats looking much better, get rid of those plasma pistols they are way too expensive for 1 ap2 shot and see if you can squeeze in another termi with a combi melta and a chainfist. combi meltas are cheap and as for the chainfist, what if you come up against a vehicle? scratch at it with your LCs?
it depends on the list about running duplicates, at 1500 you generaly only can field 1-2 non-transport vehicles but at higher points taking 2x (whatever unit) can be good for redudancy, if 1 gets destroyed it's not the end of the world you have another backing it up. An example would be if you imagine you have a vindicator and thats your big high str hitter, now 1 lucky shot takes it out of the game or it missed the target. what you going to do now to threaten that landraider full of THSS termies rolling towards you? what if you had 2 vindicators?
i'm not saying it's always good to have 2 but some things work well in pairs, defilers are another good example.
also if you have any, try out a squad (or 2) of oblits, they are simply awesome!