Yeah. Basically, you just meet with two advisers when you start so that you’re taking the right classes for both majors. U of R really does give you the freedom to structure your own education. So even if you don’t meet with an adviser for two majors, you can do the research and take classes toward a second major, then make the decision later. As long as you meet the requirements for declaring the major (right prerequisites, pass classes, not terrible GPA, etc.) you should be fine.
A side note - U of R requires that you take one or two clusters (3 courses in a related field of your choice) - one for engineering majors and two for most others. This is a substitute for gen-eds in that it still gives you a “well rounded education” but it allows you to choose something you’re interested in. Many people roll these clusters into minors or a second major.