Is this one of the same turtles that had the fungus back in December ? He did shed some but a very poor shed. Keratin layer came off "very" thin and still has pieces on his shell in his photo. Adjust his diet more and habitat. His pal yes trying to shed but still see some fungus and algae on the shell to. I would retreat both if in the same tank , it's contagious and spreads. Then clean tank well the spores are still in the tank !
Seen this happen in a few turtles at the center. Best you can do is keep using those foods but offer a "more" balanced diet with veggies too and a perfect habitat to help correct this ! Pictures are proof you still need to tweak things. This can be corrected with your help. There is documentation about wheat germ helping but it takes a year or longer in deformed shell cases to see improvement. Then more time and attention to it's habitat. Concentrate a lot on basking area with the best lighting for UVB can help like a meg ray. In the long term there are cheaper than regular bulbs. Regular UVB bulbs only produce useable ray's for a "few" months , do you have a UVB meter to check ? Most will still produce light but it's only regular light. Uvb's have a special coating on a quartz's glass and only last so long. Mega Rays are the best and last 18 months or longer. Being a "mv" type bulb it produces both UVB rays and heat so only one bulb needed for most setups. Where you would need two to three regular UVB bulb's over the same period of time. Observe what he wants to get him to bask for 10-12 hours a day! Under your setup 4-5 hr's basking is not enough. Read about basking areas , the proper heat to entice him to get under the UVB bulb needed. When I use a two bulb system I have a dimmer for the heat bulb so it can be adjusted one degree at a time until I find what works best to entice them instead of keep getting different wattage bulbs and different placement which is important for both bulbs ! Read there instructions on each box. That's why I do not recommend a double fixture for beginners , placement/ distance is different for each type bulb ! ! That is until beginners understand the difference or use a method as I do to balance both out . Under good conditions turtles will bask as much or more than swim.
Have seen some infections get into the blood stream so a vet visit for blood work may help too see if any fungus / bacteria got under the old scutes from before or an earlier date ?
Is it possible were you live to setup a safe outside habitat year round , natural sun light will help but will take a few sheds to correct. That's a few years , captive turtles don't shed every year. Note by a window will not help , UVB rays do not penetrate glass ! A must , Outside habitat's need shade areas too from the heat so he can cool down when needed !
This is someone's picture of a good shed :
https://www.reddit.com/r/pics/comments/ ... good_shed/In healthy turtles you can almost glue the shell back together and look like a real turtle shell.