Merge entries in XML

I have a XML containing products and I need to somehow merge to one entry:

<SHOPITEM>
        <PRODUCT>POINT</PRODUCT>
        <FRAMESIZE>MD</FRAMESIZE>
        <CODE>029,00</CODE>
        <COLOR>black / yellow</COLOR>
</SHOPITEM>
<SHOPITEM>
        <PRODUCT>POINT</PRODUCT>
        <FRAMESIZE>LD</FRAMESIZE>
        <CODE>029,01</CODE>
        <COLOR>black / yellow</COLOR>
</SHOPITEM>
<SHOPITEM>
        <PRODUCT>POINT</PRODUCT>
        <FRAMESIZE>LD</FRAMESIZE>
        <CODE>029,03</CODE>
        <COLOR>green / white</COLOR>
</SHOPITEM>
<SHOPITEM>
        <PRODUCT>POINT</PRODUCT>
        <FRAMESIZE>MD</FRAMESIZE>
        <CODE>029,04</CODE>
        <COLOR>green / white</COLOR>
</SHOPITEM>

The <PRODUCT> is same, what is change is the <FRAMESIZE>, <CODE>, <COLOR>.

Is there any way to get from this an usable data? The best would be in PHP, but also would be good to generate a new XML file which I can process in PHP:

<SHOPITEM>
        <PRODUCT>POINT</PRODUCT>
        <FRAMESIZE1>MD</FRAMESIZE1>
        <CODE1>029,00</CODE1>
        <COLOR1>black / yellow</COLOR2>
        <FRAMESIZE2>LD</FRAMESIZE2>
        <CODE2>029,01</CODE2>
        <COLOR2>black / yellow</COLOR2>
        <FRAMESIZE3>LD</FRAMESIZE3>
        <CODE3>029,03</CODE3>
        <COLOR3>green / white</COLOR3>
        <FRAMESIZE4>MD</FRAMESIZE4>
        <CODE4>029,04</CODE4>
        <COLOR4>green / white</COLOR4>
</SHOPITEM>