heading2doc api 插入子文档的顺序不一致

Is there an existing issue for this?

• I have searched the existing issues

Can the issue be reproduced with the default theme (daylight/midnight)?

• I was able to reproduce the issue with the default theme

Could the issue be due to extensions?

• I've ruled out the possibility that the extension is causing the problem.

Describe the problem

我在改进重构插件的拆分标题为子文档的功能，结果发现按顺序调用api的结果是乱序的。经过排查，发现哪怕手动拖动标题到文档述操作的结果也是乱序的，因此确实是api实现的问题。

Expected result

希望heading2doc的结果是确定的，无论是新插入的会在最下方还是最上方都好，但千万不要是随便找一个位置插入或上下交替插入。

Screenshot or screen recording presentation

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Version environment

- Version: v2.10.13
- Operating System: win10
- Browser (if used):

Log file

无需日志

More information

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