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This is not a "problem," it is totally normal. Let me explain.
When you updated your system, you got a new "kernel" (the heart of Linux). So now you have 2 kernels in your boot menu: the new kernel and the old kernel (plus a 3rd option for Windows). This is a good thing. It means you can test the new kernel to make sure it works well on your hardware. If you have any problems with the new kernel, you can easily boot the old kernel. It is good to always have at least 2 options, in my opinion.