Is there a way to hypothetically, combine the sigils of two entites, so you can evoke them both while only opening one sigil? Im not sure how combining sigils would work practically, but it would be cool.
For spirits, I don’t really know for sure, as I have not tried it. I would ask the two spirits individually on that matter, try it out and get back to us. But I could see it as being powerful in terms of layering sigils geared towards spell work if they are addressing different aspects of the same goal (for example, one for increasing income with one for a job promotion)
Probably not the best, mainly because some people will link two completely unrelated beings, for example Set and Lucifer and will combine their sigil to try and evoke both as one, but all they’ll get is neither or an entity or thoughtform claiming both. I don’t think combining two entity sigils into one is a good idea.
Test it out. Trial and error. There is no right way to go about doing something, right?
If you don’t feel comfortable combining them, you could just activate them both at once. If your visualization is good enough, you could overlap the seals in your head, or just place them side by side. Entities have a way of charging a room, and its always interesting to feel the effects that multiple ones have on an area when evoked at once. You can play around with the energy, and take notes on how your summons seem to interact with one another.
If you are nervous about the results, you could take things a ‘step back’ and work with elemental energy and play with them for a while, noting their effects. Then go forward with beings with connected to the elementals, and then things which have elemental correspondences. It could be very balancing or otherwise, and it will help build your perceptive powers so that you are more confident when ‘actually summoning real entities’.