Of course. However, each learner will likely find one language more difficult than the other. This does not negate my posit.Quite simple in fact. If there is the slightest bit of difference between the difficulties of learning any two languages, the harder to learn of the two is the more difficult. .It is not logical, nor accurate. The fact is that difficulty in acquiring another language is relative to a great many factors, not the least of which is what L1 a language-learner is starting from.
Languages are very complex and composed of many different aspects. Language A may have more variation in one aspect and Language B may have more variation in another, all of which is still relative to the learner's L1. "Difficult" is always going to be relative. Do you see what I mean?