I had a look at the form here.
https://singlepensionscheme.gov.ie/...Non-Single-Scheme-Retained-Benefits-Form.docx
Most of my work is with private sector pension arrangements. This type of information is required for any Occupational Pension Scheme, private or public sector, to make sure that your benefits are calculated correctly and to ensure that you're not exceeding any limits, e.g. the €200,000 overall limit on tax-free lump sums.
As you say that both of your pensions are public service superannuation, then you would complete the form as follows.
1. Defined Benefit
2. N/A (Insert name of superannuation scheme here.)
3. Address of superannuation administrator.
4. N/A
5. Date you are retiring.
6. N/A - I'm assuming that you never transferred any pension funds abroad.
7. N/A
8. (a) and (b) you insert the amounts receivable from each scheme here. You ignore (c) and (d).
You would complete the form twice. Once for each superannuation scheme.
The above replies assume that you only have two public sector superannuation scheme benefits and nothing else. It also assumes that you have no AVCs.