That doesn't look like a dual-SIM tray to me. Although what does your SIM holder look like on the other side?
This is what they might look like,
and should be marked as such. The second space is for "micro-SD" or "SIM2"
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LG's India website indicates this version can be dual-SIM.
http://www.lg.com/in/mobile-phones/lg-H860-gold
Possibly there's a single-SIM version with the same model number. Where did you actually buy this phone, in the United States?