PHP: SOAP call with duplicated keys

I have the task to perform a SOAP call with multiple elements having the same name.
The SOAP envelope structure has to be like this:

<soap-env:envelope xmlns:soap-env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="http://arubasignservice.arubapec.it/">
    <soap-env:body>
        <ns1:pdfsignaturev2>
            <signrequestv2>
                <binaryinput>ZmlsZUJJTg==</binaryinput>
                <certid>AS0</certid>
                <identity>
                    <otppwd>123456</otppwd>
                    <typeotpauth>xxxx</typeotpauth>
                    <user>xxxx</user>
                    <userpwd>xxxx</userpwd>
                </identity>
                <requiredmark>false</requiredmark>
                <transport>BYNARYNET</transport>
            </signrequestv2>
            <apparence>
                <imagebin>c2lnbklNRw==</imagebin>
                <imageonly>true</imageonly>
                <leftx>200</leftx>
                <lefty>200</lefty>
                <page>2</page>
                <rightx>200</rightx>
                <righty>200</righty>
                <bscalefont>true</bscalefont>
                <bshowdatetime>false</bshowdatetime>
                <resizemode>1</resizemode>
                <preservepdfa>true</preservepdfa>
            </apparence>
            <pdfprofile>PADESBES</pdfprofile>
        </ns1:pdfsignaturev2>
    </soap-env:body>
</soap-env:envelope>

The element which I’m trying to send as duplicate is <apparence>, however even trying different methods as suggested in multiple answers (here and here) I’m having always unsuccessful outcomes.

Hopeful someone can help me.
Thanks.