I have a two year gap and to be honest, don't stress.
You will just have to teach both kids how to play safe. I don't hide away or lock rooms for play. My kids always put stuff in their mouth but the only thing I have ever had a chocking incident with was a ten cent coin. Kids learn, if you see it in their mouth don't freak. Approach carmly and say ah ah spit it out please. Don't rush over in a panic because that is when they will likely swollow.