SPY options versions

I imagine there is a simple explanation for this, but I haven't been able to find one yet: Why are there two versions of options on SPY? For example, there are two SPY June Calls at the 94 strike: SYGFP.X, with a bid of 2.10 and another SPY June Call with the same strike, bid 2.57, ticker ROQFP.X. What is the difference between these two options, and all the other pairs like them in the SPY series of options.

Thanks for much for your answers to what may be a silly question.

 

The first expires on the 3rd friday of the month, the second on the last day of the month.

 

That explains it. Thanks.