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Your LimeSurvey version: 2.59.1
Own server or LimeSurvey hosting: 
Survey theme/template:
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Hi all, I have a survey with a prize draw that that received an influx of responses last night. Out of the fifty responses, it seems as if there are seven different people who repeatedly put in similar answers. I'm assuming these are just spam responses with the use of some auto-entry program, but I was wondering if there was a possibility of an error in the response collection/display? For some of the respondents, while 90% of their written short responses would be identical, the remaining 10% of short responses and multiple choice questions would have varying answers. 

Please let me know if I've posted in the wrong forum -  I'm fairly new to LimeSurvey and its communities. 

Your LimeSurvey version: 2.59.1

First of all, this "thing" shouldn't be on the internet anymore. LimeSurvey 2.59.1+170116 has been released in January 2017 and thus hasn't received any updates, bug or security fixes for almost 6 years now!

The 2.5x branch of Limesurvey also was probably one of the worst releases and I personally never considered this version as stable. It has been substituted by LS 3.x quite quickly due to the number of issues it had.

So I highly recommend and update to LS 5. LS3 is still supported but the underlying PHP version will be end of life soon and thus I assume that within the next 6 months LS 3 will not be supported anymore.

That being said, this all sounds like a spam attack rather than a glitch in data collection. Do you logg the IP addresses of responses?

Do you have access to server statistics? Then I would have a look at this.

if there was a possibility of an error in the response collection/display

While this can never be excluded, I would bet that this has nothing to do with Limesurvey but with spammers.