I'm sorry Ollie is having this problem. He's most likely spraying territorially, due to your other, unneutered cat, outside. However, if there is some blood in his urine when he sprays, this may indicate a urinary tract or bladder infection.
If Ollie is also using his litterbox for urination, that's good, but watch to see if he's going there, often and if only a little bit comes out each time, or nothing comes out. Male cats are more prone to develop urethral blockages, preventing them from urinating and this is a medical emergency. Because there is blood mixed in with his urine, something is bothering him in his bladder or urinary tract and it might be 'crystals', tiny, sand-like particles that have sharp edges and can clump together and form a blockage. They develop in urine that is acidic enough.
At this time, it would be advisable to have Ollie seen by a vet or ER vet to find the cause of the blood in his urine and have it treated; the vet can also make sure he's not blocked.
Your outside cat also needs to be neutered, asap. This will be healthiest for him (prevents testicular cancer), he won't be able to mate with unspayed females, adding unwanted litters to the thousands we already have, and, he will not give off a pheromone scent that's causing Ollie to spray at the window where he sees your cat.
Using a Feliway pheromone plug in diffuser will also help Ollie with the spraying, for now. Here is more information:
I hope all will be well with Ollie and you are able to get your other cat neutered. Please let me know how things are going. Thanks!
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