Laying 18mm chipboard T&G labelling over existing loft chipboard?

Hi, I've just paid a structural engineer to inspect the loft in our 1920s-built house with a view to me building a model railway layout up there. His report stated that he had 'no reservations about this being achievable since the loading of such a layout would be relatively modest, provided the number of people allowed up into the attic is restricted to two or three adults and care is taken not to jump about or otherwise impact loading on the attic floor.' There is a long central area of chipboard floor panelling up there already but parts have been installed poorly as some ends do not meet with the joists. My question is, would it be okay to lay a new section of T&G 18mm chipboard panelling on top of this existing non T&G floor just to solidify it and avoid putting a foot through the weak areas. The current panels are nailed down and I fear it will be a messy business to rip them up just to secure a few trouble spots a bit better. Many thanks, Gary