Here is the setup:

We have two TinyMCE-fields.

[CultureSpecific]
[Editable(true)]
[Display(
Name = "Main body top",
GroupName = SystemTabNames.Content,
Order = 20)]
public virtual XhtmlString MainBodyTop { get; set; }

[CultureSpecific]
[Editable(true)]
[Display(
Name = "Main body bottom",
GroupName = SystemTabNames.Content,
Order = 22)]
public virtual XhtmlString MainBodyBottom { get; set; }

They are rendered like the following:

@Html.PropertyFor(m => m.MainBodyTop)

@Html.PropertyFor(m => m.MainBodyBottom)

Nothing wierd at all, and the OPE works good, and also the "full page editing" works.

We have no special extensions, or writing any editing tags, not doing anything at all with overrides on the default DisplayTemplates for any of these fields. All is standard EPiServer 7.5.1000.0.

Problem

Sometimes, like 1 out of 20, the MainBodyTop-text overwrites the MainBodyBottom, or more likeley the text gets copied into and the BottomField. (its impossible to reproduce, it just happens)

I have checked in the database on the respective fields:

In [tblPropertyDefinition] - They are registered as two different types:

pkID    fkContentTypeID    fkPropertyDefinitionTypeID    FieldOrder    Name    Property    Required    Advanced    Searchable    EditCaption    HelpText    ObjectProgID    DefaultValueType    LongStringSettings    SettingsID    LanguageSpecific    DisplayEditUI    ExistsOnModel
127    22    18    NULL    MainBodyTop    7    NULL    NULL    NULL    NULL    NULL    NULL    0    0    NULL    4    NULL    1
128    22    18    NULL    MainBodyBottom    7    NULL    NULL    NULL    NULL    NULL    NULL    0    0    NULL    4    NULL    1

Checking the two different version on when it happens we have the following in the [tblWorkContentProperty]

Version 3708 - Before edited:

25177    127    3708    NULL    7b07c21a-7aa2-43b3-a408-f39eac087f0f    False    NULL    NULL    NULL    NULL    NULL    NULL    <p>Utbildningen riktar sig till dig som vill få tips på hur du kan ta ett första steg</p>
<h4>Ur innehållet</h4>    NULL

Version 5486 - After bug appears new version with duplicate content:

31836    127    5486    NULL    a860684f-5063-48d2-b7f4-c05c7c6f5842    False    NULL    NULL    NULL    NULL    NULL    NULL    <p>Utbildningen riktar sig till dig som vill få tips på hur du kan ta ett första steg</p>
<h4>Ur innehållet</h4>    NULL

31844    128    5486    NULL    a7dea896-0030-446e-b21d-c3fcf34a59c4    False    NULL    NULL    NULL    NULL    NULL    NULL    <p>Utbildningen riktar sig till dig som vill få tips på hur du kan ta ett första steg</p>
<h4>Ur innehållet</h4>   NULL

This happens directly, we don't even need to refresh the page, suddenly when using the OPE-editor the text is duplicated, usually it happens on these fields specifically, is it because they are named similar? We've also made tripple checks that the Model binding in the controllers are correct:

Model:
        public XhtmlString MainBodyTop { get; set; }
        public XhtmlString MainBodyBottom { get; set; }

Controller:
           model.MainBodyTop = currentPage.MainBodyTop;
           model.MainBodyBottom = currentPage.MainBodyBottom;

I am at loss whats going on here, we don't get any exceptions or anything. Might there be some old references on old page versions that points to the same field? Like if a version of a page was created before we added a 2nd field. "MainBody" was first created, then renamed to "MainBodyTop" and then in the end we added a 2nd field named "MainBodyBottom" as well. And inbeteen this page-version has never been re-saved. Can these sort of things make this behavior. Is it known? Can we avoid it somehow, by cleaning or DB or something?

Help! :)