Generally, literary journals only consider one story from an author at a time. Once you receive notification about that story, you can send another story if you want to try again. If you do follow up, read the writers’ guidelines to make sure the reading period is still open and to see if they have any additional guidelines regarding subsequent submissions. Some journals ask that you wait a certain amount of time before sending more work. Most accept your next submission as soon as they’re finished with the one before it.
There are exceptions to this general practice. Some journals—although rare—will look at more than one short story from the same author at a time. These are called “multiple submissions.” Another exception: many journals will consider more than one work of flash fiction (also called a “short short” or “micro fiction”) at a time. Poetry submissions are handled a bit differently. It’s common to send more than one poem—often up to five—in a single submission. Always check the writers’ guidelines, which will stipulate what can be sent, in what quantity, and when.