Regardless of the signature or not,you may get banned for posting consecutive times and for bumping posts if you haven't been already warned before.You might want to read through a similar case which was handled by theymos.
IIRC I did warn you about this in the past...
I would say however that I do not agree with this rule, especially when there is no paid signature involved. Posting multiple times does have clear benefits as it makes it very clear that you are making multiple points in relation to a particular topic. Making one post and then a subsequent post immediately after helps empanthesize the second post and would be beneficial to someone making a series of points concluded by a strong/important point.
Having a few consecutive posts every now and then when you don't have a paid sig isn't a big deal, but PG/GG does it habitually. The issue with this is that it unfairly bumps topics (like bumping a topic more than once per 24 hours) and it spams "watchlist", "show unrelad posts since last visit", etc.