Double degree won't really help unless it's in something directly related to a job you are applying for. Even then, that would just be a benefit to someone in that position as opposed to a negative for someone not having that experience.
It's hard to find good software developers, data scientists etc. and there's a lot of competition for top talent, I don't think you would be disadvantaged by the 3 year degree at all.
The only caveat that i'm aware of is if you are planning on doing postgrad study overseas. Most masters programs in the US expect 4 year undergraduate degrees (e.g. undergrad + honours in Australia). I haven't heard of employers expecting the same, and doubt they would care if you already have work experience.