Probably not. Note that it is the position that is made redundant and not the person. If they immediately filled your position with a new person then that would be unfair dismissal (because the position wasn't removed). The fact that you may have had work at the time you were dismissed is irrelevant. The work that you were doing will be shared amongst the others and that is okay, and makes sense.
At some stage down the track they may recreate a new position with the same role as the one you had and there is not a great deal you could do about it, and no point stressing over it.
Same thing happened to me a few years ago - I too was busy at the time but the company had to reduce FTE to stay in business (simple case of money in > money out). I wasn't the only one at the time but was suprised when I got called in.
In your case I'd expect that the two new FTE positions that they created earlier would be different in roles and pay levels - these would have been established for the long term viablility of the company.
Sometime government jobs are a little bit different though. If you had an EBA with the appropriate clauses in it, it may entitle you to refuse redundancy and force them find a new position for you - could even work out advantageous. The last job I was at was a government company and had an EBA - I knew a guy there who refused redundancy and they ended up creating the position he wanted (company went through a restructure and didn't have the roles established at the time of redundancies - very dodgy).