I'm sorry but I came with news, yes you can, I do not know at this moment if you can get more than 5 of the same, right here you can see I have 2 of the same colour with earth defense 2% of the green path, you can switch the domain for 125k on the lesser, 250k on the medium and 500k on the greater, changing it as far as I know will be done clock wise, so for example my repeated ones are light green, if i want one dark green i would have to pay 3 times 125k to move it there. first would change to red second time would change to purple and the third one to dark green
Also you can destroy the gem for the same price that cost to switch, however doing this will not return the gem to you it will only take it out of the gem alterier, so I'm pretty sure by now that you can get more than 5 of the same gem so at the end the answer you are looking for would be ,yes you can get them repeated, and what you can do is to switch them or destroy them