Is there a simple way to generate sets of sequences that re-capitulate the topology of pre-defined phylogenetic tree
Yes, what you are looking for seems to be an alignment simulator, which is quite commonly used in phylogenetics. Given a phylogenetic tree and a substitution model, you can use for instance INDELible or DAWG to simulate the extant sequences (N sequences at the tips). These programs can also simulate the indel process (gaps), which means your final sequences won't have, by default, the same length -- but you can change the settings to exclude insertions/deletions.

There is no absolute guarantee that the tree estimated from the simulated sequences will follow the "true" one (used to simulate the sequences), but they should be close enough if:


you don't simulate gaps
the branch lengths are not too short
the sequences are large enough