Spacing them out more would allow better quality on the 2nd workout. But keeping them closer together, would work more on your overall endurance.
What is important, is to try and keep the gap in between consistent, over the weeks/months.
The ideal, for an individual, would have to know: are you a rider who can go all day, but not very fast? Or are you a cyclist who can really rev it up, but for not very long? With of course, what distance you are training for?
The answers to these questions above, will guide you into taking the best decision for your abilities and goals 🙂