How can I fix this (can I fix this?)?: Posterous is duplicating my posts

Note that Posterous is shutting down on 30 April 2013

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I use Posterous to host the blog / database where I post information about job vacancies in science communication.

It goes like this - I email a post with an attachment (the job description), it publishes itself at http://scicommjobs.posterous.com and sends a tweet to @ScicommJobs. It's been doing this without incident for just over three years.

Today I realised that for the last couple of days it's been publishing duplicate posts - and sending double tweets as well. I first noticed a problem when I started receiving two 'your post has been published' emails although I didn't think much about it, assuming it to be an email glitch which has happened before.

I've sent a tweet to @Posterous and tried, and failed, to use their online contact form to submit a bug report ('Sorry, we couldn't submit your request' - not sure why).

Googling for info about duplicate Posterous posts isn't particularly illuminating and the problems people have outlined refer to something else entirely.

Is anyone else noticing this with their Posterous blog(s)?

It could well be some setting I've altered in the global 'Spaces' admin bit, although why on earth anyone would want a setting letting them duplicate their posts to the same blog I don't know.

It's also happened on another of my Posterous blogs - http://jodiepedia.posterous.com where I post audio / sound-related information and events.

If anyone has a solution that would be marvellous :)  Thanks!